Micro-segregation and residential mobility: case study of two athenian apartment blocks

This article considers changes regarding the social physiognomy of apartment blocks in urban housing in the densely built neighbourhoods of Athens City Centre. The aim is to illuminate the changes that have been a main consequence of the residential mobility that began during the post-World War II period and continues today. Thus, I will provide evidence of two apartment blocks located in the Kypseli neighbourhood of the Municipality of Athens that I have thoroughly investigated. These blocks are among the 28 I have previously examined in a project about Athenian apartment blocks.


Introduction and the origins of segregation
This paper is based on a project about Athenian apartment blocks, and it derives its theoretical context from urban and social geography.Urban and social geography are disciplines that study the relationship between the social and spatial aspects of urban spaces as well as the urban ways of being (Gregory et al., 2009).These disciplines manage to connect the social and spatial aspects and, more specifically, to examine the relationship between 'social groups' and the 'space' they manage and occupy (Jackson, 2000).Thus, in the Athenian context, the circumstances that lead to residential mobility and the consequent changes in the social physiognomy of a particular space (either a neighbourhood or the micro-scale of an apartment building) is of great importance.
The origins of urban and social geography are the work of the sociology department of the well-known Chicago School (the theoretical discussion in Sect.2.1 will clarify this connection) (Knox & Pinch, 2006).The social scientists of the Chicago School have studied the consequences (in urban life and in the relationships among residents) that they believe are the result of the urban way of life during intense urbanization (Giddens, 2009).One of these consequences is the phenomenon of 'social segregation', that is, the spatial distance between two or more social groups of the population that takes place when that population groups 'occupy different spaces within the same city' (Gregory et al., 2009, 673).The social scientists of Chicago School borrowed this term from the 19th-century study of genetics (Mendel's First Law) and used it in social science in order to describe the separation (of the ethnic groups in terms of their place of residence) they had identified (Maloutas, 2012).
The first reference to the term 'social segregation' by Greek scientists (social geographers and urban planners) was made in the 1980s and the beginning of the 1990s when there was a discussion about pre-war − the period prior World War I − segregation (Gizeli, 1984(Gizeli, , 1992;;Leontidou, 1990Leontidou, , 2001;;Nikolaidou, 1993).More specifically, Leontidou (2001, 292) mentioned in her book that since the 1920s in the Athenian area, various types of social divisions had been identified.One was the division between East (residential area of the upper-middle class social strata) and West (residential area of the working-class social strata).Another was the division between the compact central areas with their dominant type of housing, which was apartment buildings, and the popular neighbourhoods of self-construction (centre-periphery division) (Leontidou, 2001).Some of the divisions that developed during the post-war period have disappeared, such as the division between refugee settlements and natives' neighbourhoods (see also Papaioannou & Vasilikioti, 1975;Gizeli, 1984).However, the East-West and the Centre-Periphery divisions continue to exist (Maloutas, 2004).Leontidou (1990Leontidou ( , 2001) ) defined a new, exceptional type of separation that first appeared during the post-war period in the high-rise building neighbourhoods in Athens.This type is a vertical differentiation, which is segregation 1 at a micro-scale (the scale of the residential buildings), which is in contrast with the main type of segregation that differentiates the residents horizontally (municipalities or neighbourhoods are at the scale where this segregation takes place).The term vertical segregation means that a mixture of different social classes lives together in apartment buildings (polykatoikies, in Greek).These social classes dwell in apartments differentiated vertically by floor in terms of the dwelling size and the housing conditions.Therefore, different social strata occupy different apartments.The main type of vertical social segregation found in the high-density neighbourhoods of Athens is the following: the upper-middle class occupies the higher floors, while the poorest social strata occupy the lower floors (Leontidou, 1990, 234;Maloutas & Karadimitriou, 2001).
On a broader level, the phenomenon of vertical social segregation has occurred often in the countries of Southern Europe, mainly in contrast to the countries of Northern and Western Europe, where horizontal social segregation (the differentiation of the social composition of their residents per neighbourhood) has occurred more often.However, this does not mean the complete absence of the phenomenon of vertical social segregation in these countries.In many cities of Southern Europe as well as in Northern and Western Europe, the phenomenon has appeared in a different form than that of the one in Athens (Maloutas & Karadimitriou, 2001). 2 1 However, Leontidou (1990Leontidou ( &, 2001) ) avoided the use of the term 'segregation' for vertical separation.Instead, she used the term 'differentiation'. 2 For example, in central Paris, apartment buildings constructed between the last decades of the 19th century and Word War I constituted the stock where vertical social segregation was applied.The phenomenon in these apartment buildings had the following pattern which was the reverse of the Athenian pattern: the upper socio-professional classes occupied the lower floors where the apartments were luxurious and larger, while the lower classes occupied the smaller apartments in the upper floor (Maloutas & Spyrellis, 2015).Also, the The study was primarily focused on Athens for two reasons.The first reason is obvious: Athens is the case study of the research project that this paper is based on.The second reason is that the type of segregation that this research project focused on is a distinctive case within Southern European as opposed to the main type of segregation (horizontal) in the Anglo-American context.The specific study area was the Municipality of Athens where there was significant construction of apartment buildings in which vertical segregation developed (in Sect.2.2, there is more about the context in which this type of segregation developed).More specifically, during the period of intense building development from 1950 to 1980, about 35,000 apartment buildings were constructed with a land-for-flats system in various neighbourhoods of the Municipality of Athens (Maloutas, 2015). 3 As we will see through the analysis of the case studies, the changes over time in the housing and the residents in older neighbourhoods of the inner city centre have been designated in the literature as 'neighbourhood succession'.Through the analysis of this paper, I investigate the changes that have occurred in urban housing in neighbourhoods of decay that began during the post-war period and continue today and attempt to link them to the theoretical discussion about 'neighbourhood succession'.The main questions I will investigate through the analysis of the two paradigms in this paper are these: What are the changes (in terms of the mobility of the residents as well as the relations between them) that took place in the densely built neighbourhoods of the Municipality of Athens?, Do these changes constitute succession? and What is the correlation between residential mobility and social segregation?It is important to note here that my intention is not to generalise the conclusions that will arise from the study of the two cases.However, these two paradigms are indicative cases within the Athenian area and, more specifically, within the wider Ano Kypseli neighbourhood.
Subsection 2.1 provides a theoretical discussion about the concept of neighbourhood succession developed by the Chicago School.Subsection 2.2 follows with a discussion about the phenomenon of micro-segregation in the densely built neighbourhoods of the Municipality of Athens.

Neighbourhood succession: the changes over time in neighbourhoods of decay
Chicago School sociologists drew upon physical sciences to formulate 'human ecology' as the theoretical context for approaching urban space (Knox & Pinch, 2006, 161).Robert Park and his colleagues use the terminology of physical sciences, specifically ecology to explain the social phenomena observed in the field (ibid.).The influence of Darwin's theory of evolution and natural selection on shaping 'human ecology' has been significant (Gregory et al., vertical differentiation followed the exact same pattern in Naples and Montpellier.In addition to vertical segregation, there were other forms of separation on the microscale.For example, there were differences between the sides of buildings facing the street and the sides facing the inner courtyard.Over the years, upgrades to these apartment buildings, such as the addition of an elevator and the merging of small apartments to create larger ones, have brought about changes in the social physiognomy of the apartment buildings (Maloutas & Karadimitriou, 2001). 3From 1980 onwards, construction activity in Attica decreased, and its focus shifted to the suburbs (Maloutas, 2018). 1 3 2009, 395).According to the human ecology approach, in the urban space (as opposed to the physical environment), individuals compete with each other to find the most 'favourable location within the city' (Knox & Pinch, 2006, 161).This competition, based on the economic resources of individuals, results in a differentiation of land values, and thus enables one population group to gain dominance in a certain area of a city while automatically excluding others (ibid.).The consequence of this competition is 'segregation of different types of people according to their ability to meet the rents associated with different sites and situations' (Knox & Pinch, 2006, 161).So, according to Chicago School sociologists economic differentiation is 'the basic mechanism of residential segregation ' (ibid., 161).Park has described the competition of social groups in the city as follows: 'Business and manufacturing seek advantageous locations and draw around them a certain portion of the population.There spring up fashionable residence quarters from which the poorer classes are excluded because of the increased value of the land.Then there grow up slums which are inhabited by great numbers of the poorer classes who are unable to defend themselves from association with the derelict and vicious.In the course of time every section and quarter of the city takes on something of the character and qualities of its inhabitant' (Park, 1915, 579).
The metaphorical use of the terms 'neighbourhood invasion and succession' that were adopted from physical science by Burgess (one of the pioneer sociologists of the Chicago School) in order to describe the process of neighbourhood change within a city (Gregory et al., 2009, 395), subsequently constituted the dominant meaning of the term 'segregation' (Maloutas, 2004, 196).More specifically, invasion means that a new social group 'may begin to "invade" [infest the neighbourhood]' (Knox & Pinch, 2006, 322), while 'succession' is the following stage when the invading social group 'begins to dominate' the residential area (ibid., 334).The two terms 'invasion and succession' came from the dominant idea within 'human ecology' of the 'survival of the fittest' (Gregory et al., 2009, 395), in the context of the competition for the most 'favourable location' (Knox & Pinch, 2006, 161).
Chicago School sociologists, and more specifically, Burgess, in his 'zonal model' observed that immigrants of low socio-occupational categories 'are largely constrained' (Gregory et al., 2009, 395) in the high-density neighbourhoods of the city centre where they might find low-cost but poor-quality housing.Later, other immigrants who are friends, acquaintances, or relatives of the first ones, settle there (ibid., 395).The intense influx of immigrants of low socio-economic categories in the city centre bring about the invasion of these population groups (ibid.).Simultaneously, the privileged population groups move into new housing in other areas, far away from the centre, due to the increased pressure of the influx of the low socio-economic category immigrants (Knox & Pinch, 2006, 265).Thus, the Chicago School sociologists took for granted the identification of social and housing mobility, which is reflected in Burgess's model (Maloutas, 2018, 173).That is, the person who rises in the professional hierarchy will inevitably change their place of residence, thereby increasing segregation (ibid).
As a result, this process, which is described as the 'zonal model', is activated and initiates a chain reaction, whereby the residents of each successively higher status zone are forced to move further away from the centre in order to counter the lowering of neighbourhood status (Knox & Pinch, 2006, 265).Burgess described the process of inversion and succession as follows: 'Their invasion of the city has the effect of a tidal wave inundating first the immigrant colonies, the ports of first entry, dislodging thousands of inhabitants who overflow into the next zone, and so on and on until the momentum of the wave has spent its force on the last urban zone.The whole effect is to speed up expansion, to speed up industry, to speed up the "junking" process in the area of deterioration' (Burgess, 1925, 57-58).Consequently, the mobility of the residents leads to the expansion of the city (Gregory et al., 2009, 395), which results in social segregation, according to McKenzie (1925, 73-74) and Burgess (1925, 54).
The Burgess's model of invasion and succession has been criticised mainly because of the adaption of ecology as its theoretical framework (Saunders, 1986• as cited in Temkin andRohe, 1996).However, later models have used economic theory, instead of ecology in order to explain the process of neighbourhood change (Temkin & Rohe, 1996, 160).According to the concepts developed by neoclassical economics, 'social mobility will inevitably induce an individual or a household to move in order to maximize their place utility in a trade-off situation involving a number of parameters' (Bassett & Short, 1980, 27-29• as cited in Maloutas, 2004).Although the interpretation of neighbourhood change through invasion and succession shifted from the human ecology approach to an approach advanced by neoclassical economics, the correlation between residential mobility and social segregation continued to be a basic aspect among social geographers (Maloutas, 2004).
For example, scholars such as Grigsby et al. (1983, 20) in their study of neighbourhood change argued that as they grow older, the dwelling units degrade, so new households with lower incomes than the previous ones find low price housing in these dwelling units.The consequences of this may be changes in occupancy, rent value, occupants' incomes, price of housing services delivered per housing unit or in the quality and quantity of neighbourhood services provided per housing unit (Grigsby et al., 1983, 24).They also argued that the term which best describes this procedure of neighbourhood change is succession, that is, a shift in the physiognomy (regarding the characteristics of residents) of the dwelling units (ibid., 24-25).Succession can be about gender, income, social class, ethnicity etc. (ibid., 24).However, according to Grigsby et al., the most frequent type is succession occurs as a result of changes in income.'A downward shift from higher to lower income […] Such a shift is usually, but not exclusively, associated with a change in occupancy' (Grigsby et al., 1983, 24).
The criticism that has been made of Grigsby et al.'s (1983) arguments has to do with the hypothesis that forces beyond the neighbourhood, on a larger scale (metropolitan area), bring about the changes that occur in a neighbourhood and so 'there is little neighborhood residents can do to stop unwanted change from occurring because the driving forces of neighborhood change are impersonal changing conditions within various housing quality submarkets' (Temkin & Rohe, 1996, 164).These two scholars, Temkin and Rohe (1996) suggested another model of neighbourhood change according to which the social and economic characteristics of a metropolitan area affect neighbourhood stability.Specifically, they argued that the role of the social characteristics (such as neighbourhood attachment, social interactions among residents, the use of local commercial facilities and the residents' perception of their neighbourhood as a unique cultural milieu within the larger city) are very important in neighbourhood change (ibid., 166).According to Temkin and Rohe's model, neighbourhoods whose residents are characterised by strong ties are expected to reach out to institutional actors in order to maintain a stable environment in their neighbourhood (ibid.).Therefore, neighbourhood resistance is stronger in these areas which are characterised by strong neighbourhood networks.The opposite is true in neighbourhoods characterised by weak networks (ibid., 166-167).

The phenomenon of micro-segregation in the densely built neighbourhoods of the municipality of Athens
In the post-World War II period, the population of the metropolitan area of Athens was almost three times as great as it had been prior to the war (Maloutas, 2003).The urbanisation in the post-war period was due to the rural population outflow and the consequent influx of mainly new residents, internal immigrants, from the countryside (ibid.).During the Civil War (1946)(1947)(1948)(1949), immigrants from the provinces entered the big cities, especially Athens.The attraction that Athens specifically had as a relocation site for the new settlers and its connection with their choice was minor (ibid.).This choice had mainly to do with the factors driving masses of Greeks away from their rural areas, such as the protection through the anonymity that Athens and other big cities offered (ibid.).Also, the high unemployment level in the countryside drove masses of the population away from rural areas in order to find a job in Athens which offered more vocational opportunities (Maloutas, 2003;Maloutas, 2015).
Housing settlement through home ownership was the main goal of the new settlers during the post-WWII period (Maloutas, 2003).The new population which settled in Athens sought stability in securing home ownership in contrast with the volatile working environment and rented housing that could not offer this stability (Kamoutsi & Maloutas, 1986;Leontidou, 1990;Maloutas, 2003;Maloutas, 2015).
The main feature of the post-WWII period regarding the housing issue was the limited direct intervention of the state (Maloutas, 2003).The reason for this was the improvement of housing conditions, or so the government believed.It was considered that the housing issue had been solved and so a 'socially oriented intervention' was not necessary (Maloutas, 1990, 20).In addition, there were no claims for the opposite from those directly concerned.The solution to the housing issue was made in the context of autonomous practices and, in particular, through family-centred strategies, such as mutual assistance practices (Maloutas & Oikonomou, 1988).
Within this framework, the only housing programmes provided by the state, from the interwar period and mostly the post-WWII period, were the construction of social housing estates for the housing needs of refugees and internal migrants who lived in shacks in the refugee settlements of Athens (Myofa, 2023).However, because the construction of social housing concerned specific segments of the population, who were in immediate need of housing and were not included in the broader social housing policy (ibid.),this inability of the welfare state to deal with the housing issue holistically led to distinctive solutions (Allen et al., 2004).That is, the solutions that came from those in need.One of them was the land-for-flats (antiparochi, in Greek) system, which was the solution given to the problem of housing inadequacy, considering the fact that the state was unable to cope with the growing need for social housing (Sarigiannis, 2000).At the same time, but clearly with greater intensity and also to a greater extent in contrast to the construction of social housing estates (Myofa, 2023), within the Athenian area, the great reconstruction of Athens with the antiparochi system was carried out (Theocharopoulou, 2017).The antiparochi system was based on the agreement between the landowner and the builder-contractor.The aim of this agreement was the construction of an apartment building at the lowest possible cost and the distribution of the apartments to each actor according to their participation in the investment (ibid.).More specifically, the landowner grants the land to the builder-contractor in order to construct a polykatoikia (Antonopoulou, 1990).In exchange, the landowner will receive by the contractor a number of apartments in the building while a number of apartments are sold (often in advance) to finance the construction investment (ibid.).The social character of the antiparochi system has to do with the fact that many people regardless of their socioeconomic status get involved in the production process and could acquire apartments at the lowest cost (ibid.).Also, according to Theocharopoulou (2017, 111) the antiparochi system, 'worked as a mechanism for shearing wealth among the population' and so 'extreme industrialization and proletarianization' was avoided because of the development of that mechanism.That is the main reason why the system of antiparochi replace the absence of social housing in Greek case (Myofa, 2023).
This process in Athens reached its significant peak in the 1960 and 1970 s and mainly concerned the upper and upper-middle social categories (Maloutas & Karadimitriou, 2001).The first dwellers of apartments in these apartment buildings belonged to these social categories and either participated in the process as landowners, contractors, or engineers or as affluent apartment buyers (mainly occupy the upper floors) (Maloutas & Spyrellis, 2016a).In contrast with the lower (and most disadvantage) floors were destined for rent for those who could not afford to buy an apartment or those who were in transitional stages concerning their employment or students who have not become independent of the parental household (ibid.).Gradually, however, these apartments were resided in by people from a wider range of social categories (Maloutas & Karadimitriou, 2001).
The rather homogeneous structure of the polykatoikies that were constructed with the antiparochi system began to change from the mid-1970s with the relocation of a large number of residents from the upper and upper-middle social strata, coming from the neighbourhoods of the Municipality of Athens to the suburbs (north and south Athens) (Maloutas, 2004).The degradation of living conditions in the centre of Athens due to overcrowding in combination with the relocation of the more affluent households to the suburbs was the main cause (Maloutas & Karadimitriou, 2001).As a result, in Athens from the mid-1970s, the process of succession took place, where the residents of the high socio-economic strata relocated from the city centre in order to find better quality housing in their 'favourable location' (this term was first introduced by the sociologists of Chicago School, see Sect.2.1) away from the inner city.
Moreover, this residential mobility led to the phenomenon of vertical social segregation, as I discussed in Sect.2.1.This happened because, in the vacant apartments, which emerged due to the outflow of the most affluent socio-economic categories, lower socio-professional categories were installed.The segregation in these polykatoikies occurred between the upper and upper-middle social categories that remained and the newly entered lower social categories (Maloutas & Karadimitriou, 2001).Also, since the 1990s, immigrants had been looking for housing in apartment buildings in the centre of Athens, especially on the lower floors with the smallest surface, due to low rental prices as a result of the deterioration of the housing stock due to age and the worsening of living conditions in the city centre (Kandylis & Maloutas, 2017).
It is necessary to note that this stock of apartment buildings was designed in this way due to the gradation of the characteristics of the apartments per floor (the highest apartments are the largest apartments) (Maloutas & Spyrellis, 2016a).Even though there was no intention for social coexistence, it actually occurred (Maloutas & Karadimitriou, 2001).The differentiation of the characteristics of the apartments resulted in the establishment in these apartment buildings of differentiated social and/or ethnic categories and their separation per floor (Maloutas & Spyrellis, 2016a).In Athens, this model had the following pattern: the poorest social strata and/or immigrants were overrepresented on the lower floors, while on the higher floors, the higher social classes and/or the dominant ethnic groups were overrepresented (Maloutas & Spyrellis, 2015).But there are actually different forms of this pattern, as we will see through the analysis of the two case studies.
The next section will examine the methodological context of the research and, of course, of the specific study.

Methodology
The ultimate aim of my study was to determine the changes that have taken place in the vertically segregated densely built neighbourhoods of Athens.For this purpose, I focused on two apartment blocks among the total of 28 that I had investigated in the context of a project about Athenian apartment blocks4 .I focused only on two of the 28 blocks because they are located in the same neighbourhood of the Municipality of Athens, and they represent similar cases within the Athenian model.They have undergone extensive changes, such as the shift from individual ownership of the apartments to privately-owned companies (that are sometimes located far away from the country where the property is located) that have increased housing mobility and therefore changed the relationship among the residents.
The main research method the research team used was qualitative, through semi-structured, in-depth interviews with residents of the antiparochi apartment buildings.The interviews were conducted with residents of the apartment blocks that were built from 1950 to 1980 in the Municipality of Athens, where, as I have already mentioned, vertical segregation developed.The interviewees were owners (owner-occupants or, any absentee property owners or owners who used the apartment professionally) or tenants.The qualitative research was conducted during the period from May 2020-September 2021, and despite the difficulties due to the pandemic restrictions to travel and social interactions, it was completed, and the sample covers different Athenian neighbourhoods (Fig. 1).
In the next section, I will present the two Athenian apartment blocks, their histories and the changes that have taken place in them.I will focus on the interviews I conducted with three residents of the two apartment blocks.The residents with whom I conducted the interviews were: two homeowners and a tenant.Also, in each building, a basic interviewee connected me with others who knew a lot about the history of the building, its social physiognomy and the changes that have taken place.

Two athenian apartment buildings in Ano Kypseli
My examination of the two apartment blocks was to determine the changes that took place in the social physiognomy of these buildings and its consequence segregation.The two polykatoikies of the survey are located in Ano Kyspeli, a formerly bourgeois neighbourhood of the Municipality of Athens that has been in a state of decline since the 1980s (Vaiou & Lafazani, 2015).It was revitalised with the settlement of immigrants beginning in the mid-1990s as housing prices there were and have remained rather low (ibid.)until very recently.The currently increasing prices seem to be the result of a significant increase of foreign real estate investors in the market.This scenario, as we will see through the analysis that follows, applies in the two cases studies.
The first building is located very close to one of the main streets of Ano Kypseli; the second is located a little further away.The first building was constructed during the mid-1960s through the antiparochi system and the second during the 1950s.The two buildings are differentiated mainly due to their scale.The first building consists of a basement, a ground floor and five additional floors; the second consists of a ground floor and two other floors.
More specifically, regarding the first building, on the original site, there had been two houses, each two stories high.According to the main interviewee, the family of the landowner belonged to the upper-middle class.Through the system of antiparochi, they agreed with a builder-contractor construct a polykatoikia on their plot.The landowners then acquired apartments in the building, but they never lived there.Today, the descendants of the landowners have maintained the ownership of the apartments.
The basement and ground floor have no apartments, and the total number of apartments in the building is 21.Also, each floor, from the first to the third, has five apartments, while the fourth and fifth floor have four and two apartments, respectively.In terms of the size of the apartments, there is a variety from two rooms to four (approximately 130 m 2 ) as well as a small apartment (flatlet) on each floor up to the 4th.On the 5th, which is the upper floor, both apartments are large, 90 and 130 m 2 , respectively.Also, the concierge's apartment, which is located in the basement of the building, has been vacant for many years.When Fig. 1 The distribution of the project apartment blocks the last concierge retired, the residents did not hire another one, and the apartment has been used as storage space.
I interviewed two homeowners of the first building.The main interviewee, Evangelia, inherited the 5th floor apartment, which was purchased by her parents in the mid-1960s.In 1976, when she returned to Athens after her studies, she continued to live in the apartment.Evangelia has been the building manager of the condominium for several years, with the help of another dweller, Andreas.This resident is the second interviewee of this building with whom Evangelia brought me into contact.Andreas purchased the apartment on the 5th floor in 2008, and since then, he has lived there with his family; it is located next to Evangelia's.Andreas, due to his status as an assistant building manager, is in charge of collecting the building fees.Therefore, he knows (as much as possible because of the frequent change in residents) the dwellers of the other apartments better than Evangelia does.
The second building also has no apartments in the basement but has one apartment on the ground floor.Each floor up to the second has one apartment.So, the building has a total of three apartments.In this apartment building, I interviewed only one resident, a tenant.Marios is the main interviewee and along with two friends, has rented the 2nd floor apartment since 2019.This apartment, as well as the other two in the apartment building, have been owned by an Israeli investment company since 2019.
Τhe main interviewee of this building knows almost nothing about the history of the building.This is because the owner of the apartments is not an individual, but a company located far from Athens.So, when he asked the real estate agency, which is the official manager of the building, nobody could give him information about the history of the building.

The first residents of the apartment buildings and their relationship
The first dwellers of the first building were the owners of their apartments.They had bought the apartments either from the previous owner or from the contractor of the building.A prolonged period of residency had strengthened the connection among residents despite their small disagreements.The sense of community characterised the relationships among the residents in this apartment building.According to the main interviewee, who has been living there for about 50 years, the first residents were homeowners.'Ι do not idealise anything, but we all knew each other.Meetings [for managing the building] were held normally.There were disagreements (on heating hours etc.), but, okay, everyone knew each other.There was a community' (Evangelia, homeowner, 75 years old).At that time, each homeowner undertook the management of the apartment building for a year.

Residential movements, the process of succession and how the relations among residents were affected
Since the 1970s, suburbanisation, that is, the relocation of residents from this apartment building to the suburbs (North and South), has brought changes to the physiognomy of the apartment building as has happened in various neighbourhoods of the Municipality of Athens.The main change is that due to these relocations, many apartments that remained vacant (mainly those on lower floors) were reoccupied by new residents, mainly tenants.
Therefore, the number of tenants in the building began to increase in relation to the number of homeowners.However, these inflows of new residents did not bring about changes in the relationships among residents.According to Evangelia, the residents (homeowners and tenants) came to an agreement for the management of the apartment building.
This 'picture' began to change in the 1990s with the influx of immigrants from other countries who were renting apartments in this building as well as in others in the Municipality of Athens.This change has to do with the deterioration of the housing stock due to age and the worsening of living conditions, a change that according to Chicago School scientists is one of the causes of succession that eventually leads to social or/and ethnic segregation.Grigsby et al. (1983, 20), in their study about neighbourhood change, argued that the dwelling units as they grow older over time degrade, and so new households with incomes lower than those of the previous residents, as well as immigrants, find low-priced housing in those dwelling units.
The relations with the new residents were good, but were not as close as in the previous period.According to the interviewees, the different cultures between old and new residents were gradually changing the relationships among the residents.However, some of these new residents who could not afford to pay the rent every month were vacating the apartment without paying the homeowner the building fees and the rents in arrears.Therefore, it seems that the main reason for the change in the relationship of the residents was the major division of the class position among old and new residents.Usually, the financial issue was resolved with the cooperation of the building manager with the owners of the apartments, who paid their rent from their own financial resources.

Large number of vacant apartments: 'a not so classic case'
Gradually, and as a solution to this problem, the owners decided to leave their apartments empty rather than renting them.For this reason, until the middle of 2010, out of the 21 apartments (one was always empty), 10 were empty.According to Evangelia, 'the case of our apartment building is not a classic because I ask my acquaintances who live in similar condominiums and everyone is surprised with the large number of vacant apartments.Of course, I have to tell you that from the building management point of view, it was less stressful because we have no payment issue.The owners paid regularly' (Evangelia, homeowner, 75 years old).
However, based on 2011 census data, the number of vacant houses in the Municipality of Athens was 132,000 (21.7% of the vacant houses in the whole of Attica) (Maloutas & Spyrellis, 2016b).Also, the increase compared with that of 2001 (approximately 3.15 empty houses per 100 inhabitants) was significant (ibid.).Therefore, this proves that this case is not as exceptional as the interviewee thinks.

The influx of foreign investment companies and the problems in the management of the apartment building
A significant change in the social physiognomy of the apartment building occurred when some old residents sold their vacant apartments to foreign companies that either rented them out or kept them closed.Five apartments in this condominium have been owned by a Chinese company since 2016.The interviewees have not developed relationships with the resi-dents (mainly immigrants from different countries) of these apartments because of the rapid change in residents, due to the high residential mobility of these populations.Furthermore, this does not mean that all the companies that have bought apartments are consistent in paying the building fees.So, again, problems have arisen in the management of the apartment building.According to the interviewees, these issues are now harder to resolve because it is difficult for the building managers to contact the companies that own these apartments.This is in contrast to the past situation where communication with the owner or even the renter was immediate for resolving any issues.

The social physiognomy of the apartment building today
According to Evangelia and Andreas, in recent years, the specific characteristics of this apartment building are the very small number of apartments that are owner-occupied (three in total: two belong to Greek owners and one to a Cypriot student) and the increased number of apartments available for rent (12) and of vacant apartments (6).Regarding the vacant apartments, three belong to Greek owners, two to Chinese companies and one belongs to an owner from Georgia, but this one has been abandoned for the last 15-20 years.Also, in respect to the apartments that are rented, some of them are rented to Greeks and others to immigrants from various developed and developing countries (Italy, Ukraine, Albania, Nigeria, Bangladesh, Pakistan, Georgia).Regarding the changes in the demographic characteristics of the residents of the specific apartment building, while in the past, several elderly people, young people and students lived there, this proportion has now changed.Many elderly people have passed away, and the building is now mainly inhabited by middle-aged people.More specifically, of the approximately 30 people living in the apartment building, 22 are aged under 50, eight are aged 50 and over (three of them are aged 65 and over).Also, in the apartment building, there are only two children of school age.In contrast to the past, the number of nuclear families today is small (there is only a single-parent household and a household that consists of a couple with a child).The majority of households are single-member (8), two-members (3) and three-members (3).Also, there is a seven-member household (young adults from Nigeria).Thus, there has been a decrease in the number of households in contrast with the past and, more specifically, a decrease in the number of nuclear families, which according to Grigsby et al. (1983, 38) has brought about succession.'If a community lost households, some of them in the middle-and upper-income brackets, neighborhood succession (by our definition) would occur' (ibid., 38).

The model of vertical social and/or ethnic segregation in the first building
Concerning the distribution per floor, the model of vertical social and/or ethnic segregation can be observed in the specific building, as shown in Fig. 2. The separation takes place between the 5th floor that is inhabited by people in the upper socio-professional categories (mainly professionals) of Greek nationality, and the apartments on the 4th floor and below that are settled by tenants who belong to the low socio-professional stratum.Some of them are Greeks, but the majority are immigrants from economically developing countries.

A foreign real estate company is now the sole owner of the second building
Regarding the second building, I do not know much about the previous history of the building, and so I have not been able to investigate the changes that have taken place in the social physiognomy of the apartment buildings.Although, one specific characteristic of the second apartment building is that since 2019, all three apartments have been owned by an Israeli investment company which uses these as rental apartments.It is worth mentioning that each apartment previously had a different owner.So, the investment company acquired the dwellings from these various owners.This may be considered indicative of the changes that have taken place in this building throughout the years.
Utilisation of the apartments by a foreign investor is a common feature of the two buildings, the difference being that, in the second, the entire building, which is smaller in size, belongs to one investor.Also, in contrast to the first building, the interviewee of the second building is a renter.This interviewee highlighted the issues faced by a renter of an apartment that belongs to a foreign investor.

The social physiognomy of the second apartment building
Today, this apartment building is occupied by younger people from 25 to 45 years of age.More specifically, the majority of the dwellers are 25-30 years (6), while two are 40-45 years of age.The household's composition is the following: the second floor is cohabitated by three friends (not related), while on the first floor and on the ground floor, the house-Fig.2 The distribution of the socio-professional categories of households per floor and apartment in the building holds are couples with children.Regarding the occupation of the residents, there are two unemployed on the second floor, and a woman who does not work lives on the first floor; all others are employed.Specifically, there is an employee in a family business on the second floor and two employees in the private sector on the ground floor who are of African nationality.Regarding rental status, there is homogeneity since all three apartments are rented.It is noteworthy that the residents of the apartments are new residents; they did not live there before the purchase of the property by the foreign company.However, we do not know who the previous residents were, so we were not able to investigate the changes in the social physiognomy of the apartment building and analyse the changes in the relationships among the residents in the past and in the present.

The model of vertical social and/or ethnic segregation in the second building
Concerning the nationality of the residents, there is a difference per floor.On the higher second floor, the residents are of Greek nationality; on the middle floor (first), they are of French nationality; and on the ground floor, they are of African nationality.Thus, the phenomenon of vertical ethnic segregation occurs in this specific building.The residents of the dominant ethnic group living on the top floor while the residents of an economically developing country living on the lower floor.

Communication issues and the social ties among residents in the two apartment buildings
The two apartment buildings changed not only regarding the social physiognomy of their residents but also in the housing tenure and the occupation status.Regarding the occupation status of the apartments, the similarity of these two cases has to do with the involvement of foreign investors in these apartment buildings.In the first case, five of the apartments were bought by foreign companies that rent them, while in the second case, the entire building belongs to a specific foreign investor.All three interviewees mentioned the difficulties that emerged in the organisation and management of these buildings due to the tenure system.Both the homeowners-managers of such an apartment building (first building) and the renters (second building) referred to these difficulties.These difficulties have greatly affected the relations between them, in combination with the frequent change in residents.This makes it difficult to develop relations between the more stable residents (owners and renters) and those who live in apartments owned by foreign companies.

Communication issues with the owner companies
The problems in the management of the apartment building start with the lack of communication with the companies that own the apartments: 'some of the companies are unreliable and some are not.It is a slightly chaotic situation.We make a great effort so that we do not leave unpaid bills and this is a very big issue' (Evangelia, homeowner, 75 years old).The second interviewee referred to the collection of building fees issues and to the difficulties concerning the communication with the investment companies that own some of the apartments (Andreas, homeowner, 54 years old).As he mentioned, 'there are collection issues'.
Communication issues concerning the owner company were also mentioned by Mark, a renter of an apartment in the second building.More specifically, he referred to the 'impersonal procedures', as he described them, for the renting of the apartment, for the payment of the rent and for solving problems that emerged and have made residency difficult in a building that is owned by a foreign company.The interviewee mentioned that he has not met the owners because, for whatever the tenants need, they contact the real estate agency, which acts as an intermediary between the tenants and the owner company.In addition, the real estate agency is the formal manager of the building, which resolves issues that emerge.However, according to him, generally, the management of the apartment building is marginal to non-existent.As he described it, 'the selection of the house was made through more strict and impersonal ways.I came and saw it.I had no contact with the owner.The owner is in Israeli, so we communicate through the real estate agency, so as you can imagine the process of renting and solving practical issues in order to rent the apartment was very formal.We put our money in an account that is somewhere but we don't know where exactly it is.The only thing we know is that someone in Dubai manages it, and we are in a phase where, okay, we will never become acquainted with the owner!What the owner really cares about is the money and nothing else' (Mark, renter, 26 years old).

The social networks among residents
Also, as I have already described, residential mobility brought changes in relationships among residents on the micro-scale.The relations among the residents differed between the two buildings.Two of the three homeowners of the first building described the relations as impersonal and indifferent due mainly to the resident's great mobility, which leaves no room for the development of relationships among them.According to Evangelia, the community relations that had developed among the residents of the apartment building due to the long period of cohabitation (in fact, many of the old residents had lived in the apartment building since it was built) were gradually replaced by impersonal relationships.The main reason, according to her, is the brief period of the tenants' residence in relation to the changes of the dominant tenure system from homeownership to renting.So, the lack of communication due to the brief period of residence and the frequent change in the residents of the apartments are in direct contrast to the stability that existed in previous years.'The apartment building was built in the mid-1960s, and our parents were the first buyers.Cohabitation was coincidental.They did not already know each other but gradually they got acquainted.There were disagreements between residents but they were of minor significance.Then the renters that came here were as if they were homeowners.There was no difference!They helped and they participated in the management of the building.The sense of community started to change and to be replaced by other more formal relationships when immigrants from other countries dwelled in the apartment building.But we had also a good relationship with them.In the last phase, that we are in now, the new residents are literally strangers.They come, they stay for a year, they leave.Or they leave and leave others in their place that we do not know who they are.There has been no contact among residents in recent years, or there it has been in a minimal level.Because in the previous phase, when the resident was leaving, we knew the owner.There was communication.Now, with whom I am supposed to deal with, the secretary of the company?' (Evangelia, homeowner, 75 years old).
In addition, Andreas stated that he did not notice any differences in the relations between the tenants who rent an apartment that belongs to a homeowner and those who rent an apartment that belongs to a company.According to him, the main problems arise from the fact that relationships are impersonal: 'Everyone lives in their own space, and there is no communication, a warm relationship between the residents' (Andreas, homeowner, 54 years old).The two interviewees stated that the frequent change of dwellers in the apartments did not provide opportunities for the development of relationships.However, the two interviewees developed friendly relations with each other in the context of the co-management of the building and the difficulties they face.
In contrast, despite the organisation and management problems of the second building, which belongs entirely to a rather 'impersonal' company that is far away from the country where the property is located, the interviewees said that relations among the residents are good.'They are very friendly.Relationships among residents are built.We created a network.We are not in each other's house every day.But we will meet on the stairs, we will tell our problems, we will communicate, we will ask for something etc.' (Mark, renter, 26 years old).He also stated that the relations that he and his roommates have with other dwellers (who differ in terms of nationality, age, type of household and occupation) of the apartment building are more casual than formal.This is mainly based on the common difficulties they face as tenants of this apartment building.These difficulties have unified the tenants in order to organise themselves to resolve the issues that arise.After all, the small size of the apartment building may play a key role in the development of such relations among the residents.Also, the need to communicate with previously unknown people was another reason.

Conclusions
As this analysis indicates, although the two buildings seem to be exceptional cases because of the domination of renting versus homeownership, these two cases are typical because they follow the significant changes that have been taking place in the social geography of Athens since 1950.The first building has experienced periods of intense urbanisation, suburbanisation in combination with flows of immigrants from other countries, touristification, an increase of short-term rentals and the purchase of apartments by foreign companies.In the period of intense suburbanisation, the old residents move to the suburbs (due to the ageing of the housing stock and overall the worsening of living conditions in the city centre) while new residents who are mainly immigrants find cheap housing in the apartments of this building (as has happened in other neighbourhoods of Athens Municipality) that become vacant due to the movement of the old residents.The previous, more stable residents from the upper and upper-middle social strata were 'replaced' by immigrants, a phenomenon which, as I have already mentioned, is known as succession.Thus, the changes in the social physiognomy of the apartment building that residential mobility brought are the consequence of the succession of new residents of a lower social profile in contrast with that of the previous residents.This change brought about domino effect changes that had to do with the tenure system and the occupancy of the apartments.Through the years and due to financial issues that arise concerning the economic ability of immigrants to pay the building fees, the majority of the apartments have remained vacant.Later on, a number of these vacant apartments were sold to investment companies from abroad.Today, these apartments are rented.
In total, the number of apartments that are rented make up the majority, and only three are owner-occupied.Also, the number of nuclear families in the apartment building in contrast with the past is smaller.Furthermore, the majority of households consist of single-member households.
Regarding the second building, I do not know much about its previous social physiognomy.We can assume that the changes that have taken place in the first building that have led to an increased number of apartments being available for rent, in contrast with the owner-occupied units, and also to a significant number of apartments being acquired by investment foreign companies were also carried out in the second building.It should also be noted that Ano Kypseli is a formerly bourgeois neighbourhood which has undergone drastic changes in recent years.Τoday, all the apartments in the second building are available for rent, and none of them are owner-occupied.In contrast with the first building, all the apartments of the second building belong to a foreigner company.Moreover, in contrast with the first building, the majority of the households are occupied by couples with children.These households' residents are immigrants from other countries.
Also, residential mobility brought changes in relationships among residents on the micro-scale.The first building represents a paradigm of transition from the community (as it was in a rural area where impersonal relationships were the norm) to a city society (where primary relationships were replaced by indirect secondary relationships).Most likely, this also applies to the second building, although the understanding of the changes in social physiognomy of this polykatoikia is less well defined.That is because the main interviewee did not know about the relations among the residents in the previous period when the tenure system was different (i.e. when each apartment belonged to an owner).This is associated with the lack of communication with the owner company and much more with the fact that the owner company is very far from the area where the apartment building is located and therefore knows little about the rental system of the previous period.However, in contrast with the first building, in the second, the network that has been created among residents (which in some way replaces the difficulties arising from the lack of communication with the owner company) has led to a stronger resistance to changes.The residents of that building resisted changes in order to maintain a stable environment that the owner company has not provided, a phenomenon that Temkin and Rohe (1996) described in their model concerning neighbourhood change (see for more Sect.2.1).
In conclusion, as we have already seen through the analysis, the changes that took place in the specific building are the consequence of residential mobility and the influx of new residents that come in order to replace the older ones.The invasion and succession pattern defined in Burgess's model leads to social segregation.As I have already indicated, the model of vertical social and/or ethnic segregation can be observed in the specific buildings.The separation in the first building has taken place between the upper floors, where the apartments have been owner-occupied by those of the upper socio-professional categories who are of Greek nationality, and the middle-lower floors, which have been occupied by those of the lower socio-professional categories consisting of immigrants from different countries and some of Greek nationality.In the second building, there is ethnic differentiation per floor with the residents of an economically developing country living on the lower floor.