Time rupture in urban heritage: based on the case of shanghai

There is a rupture between the past symbolized by urban heritage and the modernity symbolized by urban development. This paper aims to discuss the urban heritage and its protection from the perspective of time, and puts forward the concept of time rupture. A ‘time rupture’ refers to a fault in the expression of time in urban heritage and a discontinuity of people’s sense of time. Based on a case study of Shanghai’s urban heritage, including Xintiandi, Hailun Road and Old City historical area, this paper finds manifestations of time rupture: the fading of local uniqueness, a discontinuity in the urban landscape and an alienation of the man–land relationship. Using a literature review, discourse analysis and on-site observation, this research reveals the specific problems of urban heritage protection in Shanghai. After reflection and discussion on the concept of time rupture, this paper argues that time rupture provides new possibilities for urban heritage and inspiration for urban weaving, which are concluded based on forms of past, narration timeline and heritage images.


Introduction
The road of cultural heritage protection in China can be traced back to the 1920s, and has flourished in the past three decades (Whitehand & Gu, 2007, p. 650), and China's urbanisation began to develop rapidly after the 1970s. Since the beginning of the twentyfirst century, UNESCO promotes extended approach to urban heritage that integrates social, economic dimensions with built environment, and since then urbanisation has increasingly been considered alongside heritage preservation. In the coexistence of them, the sense of place and time are weakened and blurred, and the time becomes discrete and discontinuous. Cities symbolise modernisation, sparking innovation and development with high-speed changes and colliding interests and ideologies, while urban heritage represents the cities' past, conveying a local consciousness and communicates collective memory. Under the trend of urbanisation and decentralisation, urban heritage has formed a trend of fragmented and regional manifestation, so the various levels of urban heritage are not chronological order but interwoven and differentiated.
Time rupture is a fracture in the expression of urban heritage in time and a resulting discontinuity of people's sense of time (Wang, 2020). The occurrence of a time rupture is closely related to urban development. The history, development track and cultural accumulation of a city affect the relationship between man and land and determine the Abstract There is a rupture between the past symbolized by urban heritage and the modernity symbolized by urban development. This paper aims to discuss the urban heritage and its protection from the perspective of time, and puts forward the concept of time rupture. A 'time rupture' refers to a fault in the expression of time in urban heritage and a discontinuity of people's sense of time. Based on a case study of Shanghai's urban heritage, including Xintiandi, Hailun Road and Old City historical area, this paper finds manifestations of time rupture: the fading of local uniqueness, a discontinuity in the urban landscape and an alienation of the man-land relationship. Using a literature review, discourse analysis and on-site observation, this research reveals the specific problems of urban heritage protection in Shanghai. After reflection and discussion on the concept of time rupture, this paper argues that time rupture provides new possibilities for urban heritage and inspiration for urban weaving, which are concluded based on forms of past, narration timeline and heritage images.
Keywords Urban heritage · Time rupture · City weaving · Urban landscape degree of local uniqueness (Labadi, 2016). Shanghai, located in the middle of the east coast of China, has convenient transportation and a massive population. In 1843, according to the Treaty of Nanjing, Shanghai was officially opened as a trading port. Subsequently, France and the United States successively set up concessions, opening a century-long history of concessions in Shanghai. The special social background and geographical location gradually made the business and economy of Shanghai prosperous. The relatively stable and peaceful environment in the concession areas promoted the development of the population and culture. Different architectural styles and cultural forms have successively emerged, laying the foundation of diverse culture. At the beginning of the twentieth century, significant political events and cultural activities occurred in Shanghai, such as the June Third Strike in 1919 and the First National Congress of the Communist Party of China in 1921. These landmark events left a deep mark on the image of Shanghai. Subsequently, the turbulent situation made the city in constant change and unstable. After the founding of new China, the management and development of Shanghai gradually returned to order. After the reform and opening, Shanghai developed rapidly and became the economic, financial and trade centre of China and even the world.
Shanghai was chosen as the focus of this research for the following reasons. First, urban changes in Shanghai have been quite intense in the past few decades, and the current degree of modernisation is high. These factors indicate Shanghai is suitable as a sample to explore the relationship between cultural heritage protection and the dynamic urban landscape. Second, due to the high overall level of education, economy and culture, the establishment of the heritage protection system in Shanghai has brought together various forces. After practices and explorations, Shanghai has become a model for many smalland medium-sized cities in China. China's urban heritage working is faced with many problems including the loss of cultural authenticity, obvious homogeneity of cultural landscape, excessive commercial development, and lack of relevant laws and regulations (Zheng, 2020). In-depth study of Shanghai will help to quickly cut into these problems faced in China's urban heritage protection and development as well as providing constructive solutions.
In this paper, I use 'time rupture' to describe the contradiction between urban heritage and urban environment, which reflects the impact of urban regeneration on urban heritage. From the perspective of the change of urban heritage and the dual relationship between people and the city, this research explores the presentation and logic of time rupture. This paper attempts to discuss the following questions: What are the manifestations of time rupture in the urban environment of Shanghai? How to reflect on heritage protection from the perspective of time rupture and what are the effects of this kind of rupture?
The following section explains the origin and background of the problem as well as introducing the concept of time rupture by reviewing the idea and concept of time. The main theories of urban heritage and practice in Shanghai are summarised. The third section introduces and explains the selection and implementation of the methodology. The fourth section describes the three signs of the time rupture of urban heritage through on-site observation and archival studies of the heritage areas of Xintiandi and Hailun Road in Shanghai. The last two sections are questions and reflections on Shanghai's urban heritage protection, attempting to explore the work direction and focus of urban heritage from the perspective of time rupture. Through research on this topic, I hope to make clear the problems and difficulties of heritage protection in the process of urban development from a perspective of time. The goal is to extract new phenomena of urban heritage from a dynamic context and provide strategies for improving the protection system and adjusting the protection concept.

On time rupture
Time rupture includes two concepts: time and rupture. In this section, I first untangle the understandings of rupture from various fields, which leads to the perspective of rupture discussed in this paper. Next, I introduce different concepts of time, thus clarifying the definition of time rupture.

Concept of rupture
The concept of 'rupture' has received continuous attention in French ideological circles. For instance, Bachelard took a clear stand against 'theory of duration' (Bergson et al., 1911) and believed that the essence of time lies in the sudden moment (Bachelard, 2013, p. 18). Althusser's 'symptomatic reading' (Althusser et al., 2016) refers to a theoretical framework of a text according to the symptoms of the text, such as 'word', 'blank', 'silence', and others. He also firmly adheres to the theory of break, believing that temporality is the essence of the formation and development of cultural forms and that real history lies in a complex temporality. In For Marx, Althusser (2005) showed that although we recognise the continuity of various cognitive fields, we also insist that when these cognitive domains break, they create a new logical rule. Macherey (2006, p. 85) opposes that structure is only used to reveal the clues of 'absence' in the works, and these 'absences' or 'silences' are the real meaning of the works. These ideas seem to be useful for thinking about heritage, because focusing on the 'rupture' is the way to glimpse where conservation is weak or the urban landscape is dissonant. This research attempts to explore if the concept of rupture could provide inspirations for the reflection of cultural heritage protection.
The discussion of the concept of history in the field of philosophy also involves the problem of rupture. Benjamin (2009) rejected the homogeneous and empty view of history. he maintained that historical materialism could fracture the continuous process of historical unification rather than simply measuring history with time only (Benjamin, 2009). Adorno, in contrast, highly praised the discontinuity and disharmony of works. He (as cited in Chen, 2005, p. 281) believed that the internal contradiction could highlight the value of harmonising the internal inconsistency more vigorously than false and superficial harmony. Foucault's idea of rupture is the core content of 'knowledge archaeology' (as cited in Zhang, 2006, p. 45). He advanced the notion of the discontinuity of history and introduced the concepts of rupture and boundary into a comprehensive historical analysis from a theoretical perspective. The discussion of the concept of history provides a perspective to consider the conservation of heritage. It might be bold to suggest that the value of preserving heritage is better highlighted by the phenomena of rupture in it.
In the exploration of modernity, the concept of rupture is used to discuss the collision in social processes. Giddens (2008, p. 3) maintains that rupture is one of the remarkable characteristics of modernity. In many key aspects, there are discontinuities between modern and historical aspects of society. He proposed that rather than labelling the current society as 'postmodernism', it is better to conduct an in-depth study on the characteristics of modernity. Hassan's theory (1987) is prominent in its use of a framework of binary opposition. He juxtaposed modernism and postmodernism, comparing their respective characteristics. He believed that in cultural thought, uncertainty fills the space, which includes pluralism, fragmentation, contingency and more. Hassan holds that the historical process is both continuous and fractured, and that these two views are both narrow and complementary (as cited in Mao, 2015). The reflection and discussion of modern society and historical processes from the perspective of continuity and rupture inspired my focus on continuity and rupture in urban heritage.

Concept of time in different contexts
Time's relationship to the economy, politics and culture is a complex discussion in different contexts. In the West, for instance, people have different views of time. In ancient Greece, different city-states formed their own calendars. Sometimes one city-state used two kinds of calendars, one for religious festivals and the other for political rule. The evidence shows that different festivals were expressed as different times, which is reflected in the boundary between secular time and sacred time. For example, the relationship between master and servant is reversed during the festival of Saturnalia in Rome, which reflects the discontinuity of time (Gardet et al., 1988, p. 151).
In ancient Chinese farming civilisation, the concept of time relates to the specific concept of season. From a natural level, the four seasons symbolise the change of climate. From a humanistic level, time is closely related to human activities, which guides people's daily life and labour rhythms, affecting national policy-making and moral education. In traditional Chinese culture, the expression of time is quite complex. The time of a year is divided into spring and autumn at first, and then into four seasons-spring, summer, autumn and winter. In the traditional calendar, a year is divided into eight sections: spring begins, vernal equinox, summer begins, summer solstice, autumn begins, autumn equinox, winter begins, and the winter solstice. After that, time was further subdivided into 24 solar terms according to the changes of natural rhythms. The ancestors conformed to the farming season and formed their cognition of the laws of climate and yearly seasonal change by observing the movement of celestial bodies. This is the product of an ancient farming civilisation, which expresses a concept of time that maintains people are closely related to all things in the universe.
In the Yellow Emperor's Canon of Internal Medicine, it is recorded that: 春生, 夏长, 秋收, 冬藏, 是气之常也, 人亦应 之, 以一日分为四时, 朝则为春, 日中为夏, 日 入为秋, 夜半为冬。 [It is the general rule of the four seasons of a year that the Yin and Yang of the human body changes accordingly. The morning is like spring, noon is like summer, evening is like autumn, and midnight is like winter.] The concept of the unity of humanity and nature is contained in the notion of time in ancient China. The division of time is based on the laws of nature, the agricultural seasons and the recognised social morality. Therefore, time is not only measured in a physical sense but also contains a humanistic significance from the state to the people's livelihood. Ancient China followed a form of commune life (Gardet et al., 1988, p. 56), that is, individuals depend on the extended family or clan to which they belong. Regarding the economy, culture and population, state organisations have always depended on the mutual assistance and concentration of clans. Therefore, the extension of race and the memory of the past always run through people's thoughts, showing a kind of continuity.
Over the course of history, philosophers began to think about the society from the perspective of time. Time is regarded as a variable with constructive power. In modern society, in most cases, people use the time shown by the clock pointer to specify their concept of time; however, this is only a concept of time constructed in the context of the industrial age to unify social activities. Time, like language, is a kind of convention, born out of people's different grasps of the surrounding natural and social environments (Zhang, 2015). Elias (1993, p. 37) proposed that time presents the characteristics of a cosmic dimension and is a symbolic expression of experience. The construction of time differs in various periods and civilisations or even in the same civilisation, where there are obvious divergences in the concept of time in different periods and regions. It can be concluded that time is constructed in the process of human participation, as even the most widely recognised time order has different time concepts and psychological perceptions.
The concept of time is closely related to society and people, and presents different characteristics in different contexts. Time highlights the transitory nature of social relations, while simultaneously showing how social relations surrounding the structuring of time-space are underpinned by power. I suggest to take time into account as an implicit and discriminating factor which projects itself on historical buildings. Introducing the perspective of time into the discussion of heritage will form a dynamic and changing method to analyze the protection of urban heritage in the current social context. This paper mainly discusses two kinds of time: time represented by heritage itself, which is a physical dimension of time. The second is the sense of time at the cognitive level of individuals, that is, the subjective consciousness of continuity and sequence, without timing tools.
The time rupture in the heritage context In the context of heritage, there are not many works on time rupture, and the concept is vague. Kasemets (2015, p. 99) explained the idea of time in ruins in Ruptured Landscape, believing that a rupture of time could be described as the transcendence of natural time over previous social time. Hartog (2005) proposed in Time and Heritage that heritage is a sign of rupture between the present and the past, which is the actual experience of accelerating the transition from one memory state to another. Based on the statements above, this paper defines time rupture as the breakpoints of heritage in time expression and the discontinuity of the sense of time.
'Weaving the city' method in shanghai urban heritage protection In 2002, Shanghai promulgated the Regulations on the Protection of Historical Cultural Areas and Excellent Historical Buildings in Shanghai (上海市历史文 化风貌区与优秀历史建筑保护条例), which specifies protected objects in detail. These include areas and neighbourhoods with concentrated historical buildings and a landscape that reflects the regional cultural characteristics of Shanghai, as well as traditional workshops and old warehouses of great significance in China's development history or related to important events (Shanghai Municipal People's Congress, 2017). In Shanghai's heritage protection practice, the concept of 'weaving the city' is often mentioned. This concept means to create a smooth and gentle transition between the new city and the old city to minimise the damage to the historical landscape and simultaneously stabilise the lifestyle and structure of residents. As an advocate of China's weaving cities, Professor Zhang Jie (cited as Shen, 2012) proposed that large-scale demolition and construction will have an irreversible impact on human settlements. Urban planning and renewal should respect the rhythm of the main body of human beings rather than create a large span between the traditional and the modern. The vivid word 'weaving' reminds me of rupture, which has an opposite meaning. Combined with my previous discussion on time, I attempt to explore the rupture of urban heritage in the perspective of time.

Methods and methodology
This paper adopts a qualitative method to study the development of urban heritage in Shanghai's old town area by means of a literature review, discourse analysis and on-site observation after establishing the research problems. The specific phenomena are transformed into abstract laws, and the internal time logic in explicit urban heritage is revealed.
A literature review is a systematic review or evaluation of documents that seeks to obtain meaning from data and employ prior knowledge (Bowen, 2009). In this research, I put forward the new concept of time rupture. In order to form the concept in the context of this paper, I sorted out the relevant literature related time and rupture respectively and finally made a summary. This research selected Xintiandi, Hailun Road and Old City area as cases, so the planning documents and local chronicles of these districts have been mainly searched and analysed. Literature review is used to build the concept frame and research background. The comparison of maps is also used in this study to illustrate that the demarcation between tradition and modernity is very blurred, which reflects the complexity of different time in city.
Discourse analysis is effective in the research of social phenomena. From the analysis of the wider social situation of language use, great significance can be obtained (Drid, 2010). This research extracts the nickname of Shanghai and the evaluation of urban heritage protection by experts and scholars to analyse the subtle relationship between people and the city and interpret the collision of different time concepts in the urban environment. By analysing the Regulations on the Protection of Excellent Historical Buildings and Historical Cultural Landscape in Shanghai, this research concluded the focus of official discourse in heritage protection. Literary works and traditional concepts are also referred to reveal the man-land relationship in Shanghai.
On-site observation is based on carefully selected samples, including the distribution and function in the shikumen building area, the behaviour of passersby, the surrounding environment of the Hailun Road area in the Hongkou District, and the ecology of the Old City residential area. I use images, observation and record to explain the coexistence of old and new in urban environment and the life scene of the residents in the old districts. Through the rupture represented by these cases, this study further analyses the problems and seeks breakthroughs.

Temporal markers of time rupture
Since the founding of the People's Republic of China, urban changes in Shanghai have been more severe, and the integrity of the urban texture has been destroyed. The fading of local uniqueness, the discontinuity of urban landscape and the alienation of the man-land relationship are the main temporal markers of the time rupture of Shanghai urban heritage.

The fading of local uniqueness
In the old town area of Shanghai, urban renewal and urban planning oriented by the land economy have gradually blurred the perceptual side of the city. The local uniqueness has been reduced by the high speed of modernisation. 'shikumen' is the most distinctive residential style in Shanghai. Born out of the traditional Chinese courtyard, shikumen style is named after the use of stone for the door frame in the process of improvement. This architectural form maintains the symmetry of the central axis of Chinese traditional architecture, but the overall distribution adopts a European style. Some shikumen buildings imitated the style of traditional buildings in the south of China, while some were influenced by Western architectural styles, using various kinds of flower patterns as decorations on the door heads. Shikumen houses not only display an architectural style combining Chinese and Western styles under the specific historical background of Shanghai, but also carry the close neighbourhood relationships in the Longtang community.
Xintiandi was once an old area of shikumen buildings and was a symbol of modern architecture in Shanghai. It is in the centre of the city, on the south side of Huaihai middle road. Now it is a comprehensive promenade integrating catering, shopping, entertainment and culture. In the minds of tourists at home and abroad, Xintiandi is a landmark showing the characteristics of Shanghai, so there is often a massive flow of people here, even during the epidemic (see Fig. 1).
The area where Xintiandi is located typically reflects the time rupture of urban heritage. The exterior of the shikumen building is still there, but the interior of the building has been transformed into shops, restaurants and bars with different styles. On the signboards in the shops, we could also see the ancient door head at the entrance of the building (as shown in Fig. 2 below). This kind of splicing shows fragmentation. The original residence function of shikumen has been changed, and the primitive inhabitants of shikumen buildings have left. Xintiandi has been built as a landmark for tourists at home and abroad to experience 'Shanghai style'. However, this 'Shanghai style' may only be reflected in the appearance and form of the buildings. The brand of the global chain that is visible everywhere in Xintiandi has already made it fall into homogenisation (see Figs. 3 and 4). When people travel in the lane of Xintiandi, they could still touch the old-day Shanghai from the last century. Yet when they enter the interior of the building, the fashionable shop shows the time of delocalisation.
The difference between the internal and external functions of the building has become the most There is an old shikumen house near the entrance to Xintiandi, which is the site of 1st National Congress of the Communist Party of China. It witnessed the birth of the Communist Party of China and was an important milestone in Chinese history. People walking in front of this historic building are slow and solemn. However, a few steps away, the pace of people in Xintiandi commercial district is brisk. Within a short distance, the individual behaviour of the crowd presents a heterogeneous sense of time.
Whether focusing on the global environment or a particular place, the concept of time is not unitary. Because time has no measurable entity, people's sense of time is often diverse, especially in the level of individual cognition: private and public, intentional and unintentional, active and passive, and more. If there is a difference, there would be a rupture. The presentation of individual sense of time under the background of urban heritage has become a necessary element of urban landscape.
In Shanghai, the discontinuity of sense of time often appears in the innovation and transformation. As David Harvey (2003, p.1) pointed out, the concept of rupture contains a certain degree of universality and persuasion. In front of a large amount of existing evidence, things that should not or could not have happened. I think this kind of rupture can be described as a kind of abruptness, the emergence of new things in the traditional environment, or the unexpected phenomenon in the formed habit of daily life. When gentrification and commercialisation swept through urban heritage, the original functions of many traditional buildings have been transformed into commercial areas or tourist attractions. The residents who once lived in one place were moved to other places due to city renewal and relocation. Once the time trajectory of the region is interrupted, the uniqueness would be gradually reduced.

Discontinuity of urban landscape
When discussing the temporal and spatial state of urban heritage, the concept of urban landscape must be mentioned. Urban landscape is the revelation and expression of urban intention from multiple perspectives, and the interpretation of urban characteristics from material and non-material fields. Tiamsoon Sirisrisak (2012) summarised the elements of revealing and expressing urban landscape, including six tangible elements: architecture, skyline, urban space/ circulation type, view/scenery, small-scale elements / design decoration, vegetation, and intangible elements such as urban function, place names/dialect, social events/traditions, story/history, lifestyle, food, local belief and wisdom.
Shanghai's 12 historical and cultural areas are all distributed in the Puxi area (west bank of Huangpu River, old town in the traditional sense) of Shanghai. These areas are not only the root of Shanghai's historical context, but also the centre of city's commerce and business. Both business circles and office buildings are relatively dense. From the comparison between the distribution map of Shanghai's historical cultural areas (see Fig. 5) and the distribution map of Shanghai's commercial area (see Fig. 6), it can be seen that there is almost no boundary between tradition and modernity. Busy office workers shuttle between the office buildings, while the elderly residents are leisurely walking in the alley. These scenes coexist in the same space, and the material and nonmaterial elements are interwoven, forming the rupture of urban landscape.
Near Hailun Road in the Hongkou District, the time rupture of the urban landscape is more obvious. Standing at the crossroads and looking far away, the most representative high-rise buildings in Shanghai (Shanghai Tower, Shanghai World Financial Centre For an international metropolis like Shanghai, it is difficult to achieve a consistent time order, and the discontinuity of the urban landscape has become a significant mark of time rupture. The non-material elements of the urban landscape are also ruptured. Taking dialect as an example, the decrease of local dialect popularity and the mixture of multi-language codes are signs of time rupture. The Shanghai dialect is a kind of Wu Chinese and has thousands of years of history. The phonological changes of Shanghai dialect are slower than those of northern Chinese dialects, leaving traces of ancient Chinese. Some ancient poems and articles read in the Shanghai dialect could reproduce the ancient rhyme better than Mandarin. Just like living fossils, it inherits Shanghai culture and remains traces of contact between local dialect and foreign languages during the concession period (such as Pidgin Shanghainese), which is a living cultural relic. However, under the background of a common language (Mandarin) promotion, it is rare to hear local folk songs and nursery rhymes from people. Many new Shanghainese working in Shanghai have brought different local accents. The staff of enterprises all over the high-end office buildings speak standard and fluent Mandarin and freely switch in multiple languages, leading to another language trend. Even the younger natives cannot or do not often speak Shanghai dialect, and the continuity of dialect is significantly weakened, and the various accents in the city have brought a fragmented sense of time.

The Alienation of the man-land relationship
In the public description of Shanghai, we can see the apparent estrangement between people and the city. For example, Shanghai has a well-known nickname of 'Magic City' (Muramatsu, 2018), which precisely describes that Shanghai is unpredictable and hard to define. Some people say that Shanghai is a vast show, displaying the delicacy and prosperity after filtering, which means that the bare humanity is screened out from the well-known image of Shanghai. In the traditional concept, people often say that Shanghai is too material. Smart calculation and high efficiency are the characteristics of this city. These views may be one-sided, but it is undeniable that in a city full of competition and interests, the relationship between people and resources is utilitarian. 'Shanghai is a city, not the hometown of anyone' (Sun, 2001, 1). This sentence of a Shanghai writer encapsulates that people struggle in the urban environment and pursue efficiency and wealth, but it is difficult to develop intimacy in the urban environment. Tuan (1990) mentioned in Topophilia that people's familiarity with the environment could easily lead to a sense of attachment. Just as people always use the sweetest and most longing tone to describe their hometown, even if this emotion is more inclined to a kind of fantasy and reverent psychology. However, the emergence of big cities makes the relationship between people and places tend to be alienated. People living in big cities change jobs and move houses frequently, striving for the best choice among the rich opportunities. Therefore, the state of man and place is unstable. The former suburbs may become today's urban areas, and the former residential area may become today's commercial centres. The urban space is challenging to grasp, and the relationship between people and space is fragile. In Shanghai, the alienation of man-land relationship is commonplace. The new citizens who are constantly pouring into the city have more functional needs than emotional dependence. The accelerated flow of various elements in the perspective of globalisation exacerbates this alienation. Jackson (1995) states that people associates a sense of place not so much with architecture or a monument or a designated space as with some events, so he believes it is the sense of time that creates the sense of place and community. When producing an awareness of our belonging to a city, what we actually share is a sense of time, a temporary order that is commonly shared by social group. In the past, people tend to attach themselves to 'organic and functional periodicity' (Zerubavel, 1985) which is dictated by nature, while in the modern urban society, however, the social life is temporally structured by mechanical time. In Shanghai, urban citizens rarely share a common schedule together, instead, individual has own living rhythm which has a kind of exclusiveness. This results in the downgrading of places and the increasing alienation between people and urban space. During Shanghai's Covid lockdown period in 2022, the man-land alienation become more obvious. Almost all the people have to remain confined to their homes for more than 2 months. Cinemas, museums and other cultural places remain closed and all the urban space becomes empty and lack of meanings. Consequently, people lose the connection with most urban spaces and this marks the disappearance of both temporal and spatial distinctions.

Evaluation and weaving of time rupture
As an international city with a high degree of modernisation, Shanghai has been exploring and optimizing the protection strategies of urban heritage to coordinate the sustainable development of various social elements. From the protection of symbolic buildings to the maintenance and display of the overall urban landscape (Shao, 2016), Shanghai has made a more in-depth practical exploration of the protection of urban heritage.
Time rupture is a neutral concept from the perspective of urban heritage protection. Time rupture does not mean collapse or termination; on the contrary, it provides soil for the collision of multiple time concepts. In the urban environment, using this kind of rupture to open new space seems to aggravate the degree of the rupture, but in turn, it also makes different time levels become closer. We should not only pay attention to the problem breeding from the rupture, but also focus on timely adjusting the protection concept in the construction of the city with huge space, and look for more scientific city weaving possibility, to achieve the balance and sustainable cooperation of various resources in the urban heritage.
Make heritage protection connect with diverse forms of the past The coexistence of old buildings and new buildings creates time rupture, thus producing diverse 'timespace'. According to Massay (2004), the aggregation of partial timespace rhythms of individuals present at typical locations in typical times may help establish a specific place temporality, and this temporality can contribute to produce identity of place. In urban heritage protection, different temporal attributes of heritage site can be connected together to form unique distinctiveness.
Columbia Circle is a typical case of time rupture in Shanghai's urban heritage. It was built in 1920s as a social hub for Shanghai's American community during Shanghai's grand epoch. This historical site is constituted of preserved colonial monuments, former industrial buildings and new modern buildings, including Sunke Villa, Shanghai Institute of Biological Products, etc. Due to the nature of the institute and its disconnection from the surrounding urban environment, the compound was developed in a vacuum, which was separated with other urban areas. The site displays a cross-section of twentieth century Shanghai, with buildings built at different times and in different styles.
Before regeneration, this site can be regarded as a time rupture point in Shanghai, it is out of line with the contemporary urban environment and the internal landscape is discontinuous. The regeneration strategy considers different architectural layers stretched over time, and combines both the monuments and the industrial buildings with the introduction of three new buildings, redeveloping this site into a lively public area with commercial and cultural spaces. According to the designing and planning team, they proposed a specific program and architectural transformation aiming to form a rich collection of spatial typologies and attract a broad public. It is reported in the news that Columbia Circle is a dialogue between old and new buildings across time and space (Zheng, 2021).
The regeneration of Columbia Circle makes the isolated and idle urban space accessible and experiential, achieving a harmonious relationship between different historic layers and extending the repertoire of spaces. In less than a year, Columbia Circle has become a popular place for the daily leisure and recreation of the surrounding residents, but also a new fashion landmark in Shanghai, gathering a large number of trend brands and stores. At the same time, various large-scale art exhibitions, seminars and special lectures also inject vitality into the cultural life of citizens. This kind of conservation connects the historic buildings with the diverse forms of the past well, which introduces new materials and new functions to the site that are complementary to those existing.
Replace mega-narrative with micro-narrativecomplete the timeline It is generally believed that heritage comes from the past, which influences the present and leads to the future (Nilson & Thorell 2018), existing throughout all time and space. Its depth and breadth are far greater than each individual can grasp the time and experience. In other words, the time expression of heritage is macro, just like a continuous network, running through different individuals, times and cultures. The death of an individual represents the disappearance of a narrative subject and personal memory. Time rupture appears between the accumulation of urban heritage and the fragmentation of individual life, which provides the point to bridge the time breakpoint of individual life and death by connecting collective memory.
The government-led regeneration can be defined as a 'mega-narrative', carrying out large scale planning and construction projects but neglecting many 'micro factors' such as urban texture, sense of community and public participation. It is gradually becoming the consensus that the era that Shanghai relies on large-scale construction of urban space has ended and urban planning need to constantly regenerate and optimise urban space instead of pursuing 'metanarrative'. Recently, some of urban regeneration practices begin to focus on the 'micro' perspective of heritage protection. For example, the regeneration work of Wukang Road, a cultural historic building in Shanghai's old urban area, tries to combine old building with residents' daily demands. The community encourages residents and designers to jointly propose their demands to identify the space that needs improvement, and finally establishes an 'urban regeneration project database'. This is a typical example of the transformation from 'large-scale demolition and construction' to constant and slight regeneration. This is an effective attempt to weave urban texture.
Since 2014, with the support of district administration and residents, an oral history project of Wukang Mansion started. The team interviewed residents for more than half a century, building managers and chief planners of the building. After 6 years of work, the book Living in Wukang Mansion was published. This project presents the daily life and collective memory inside Wukang Road with an individual perspective, retaining the memories of urban people and rich details of urban history in great changes. In this way, fragmented cultural memories are strung together the timeline of urban heritage is becoming complete. Time rupture is a kind of rupture of narrative, thus, focusing, collecting and recording the timeline of narrative is essential for weaving time rupture. It is worth emphasising that a more micro perspective is promoted in urban heritage conservation.
Break the single situation of urban heritage image Foucault called places such as museums 'heterotopia' (2006). In these kinds of places, time has been gathering and inhabiting the peak of time. This place is independent of time but contains all times and forms. It is an infinite, continuous accumulation of time. Starting from Foucault's theory, we can call all heritage heterotopia. Foucault has argued that there is no monoculture in the world that has not established heterotopic. Heritage sites can be regarded as time capsules filled with history, artefacts and traces of the past, some are visible and some are invisible. Time rupture in this research describes the heterogeneity of urban heritage, which calls attention to the complex temporality contained in the heritage.
The rigid image of urban heritage quickly leads to the neglect of other historical landscapes. Shanghai shikumen architecture is the focus of attention in the field of architecture. It has been established as the image representative of Shanghai modern city texture, but it seems to be the only representative. When shikumen architecture becomes the focus of the old city protection and the highlight of heritage tourism, the evolution of urban morphology, traditional lifestyle, wharf culture, and Shanghai dialect culture, which are also the constituent units of urban texture, lacks attention. The public's cognition is superficial, and the time rupture needs to be bridged. It would be dangerous for a city to rely too much on strengthening an image (Denslagen, 2009, p. 37). As a historical legacy of the city, the types of urban heritage should include not only the dominant heritage types such as monuments and historic buildings but also the hidden heritage types such as city stories, grass-roots culture, dialect changes, and more, which are gradually blurred or even declined with the modernisation of the city.
Besides, a 'Deep Cities' approach (Fouseki et al., 2019) can be utilised in urban heritage conservation. This approach sees cities as spaces that comprise multiple and complex, temporal interrelated layers and regards urban changes as heritage value. Time rupture exactly causes people to notice the multi-temporality of urban heritage, which is a dynamic perspective well suited in the study that alternates between the contemporary and the past. For example, research on how history and heritage can be linked to a selection of key symbols or to a composed and designed reactivation of historic traces can help to provide suggestions on urban planning. Summarising ways in which multi-temporality and historic traces are used in urban context, including naming, contrasting old and new structures, relocating historic fragments and embedding them with symbolic meanings, converting old functions into modern constructions, may be a good way to innovate heritage interpretation.

Conclusion
In the urban environment, cultural heritage faces a broader development space and greater uncertainty. The process of urban regeneration led to the destruction of the integrity of urban texture and the discontinuity of the urban landscape, which is the materialisation of time rupture proposed in this paper. From the perspective of time, there is a collision and interweaving of different time concepts and expressions between urban heritage and the modern city. Therefore, this paper proposes the concept of time rupture, defined as the discontinuity on the dual levels of the heritage landscape and heritage cognition. Time rupture entails a rethinking of urban space, using time to visualise the heterogeneity of urban heritage.
In related research on urban heritage, there are many studies focusing on the heterogeneity of urban heritage from the perspective of physical space, but few cases take time rupture as the breakthrough point. This research employs Xintiandi, Hailun Road, and the Shanghai Old City as samples for observation and analysis. Through a literature review, discourse analysis and on-site observation, I assess the mapping and logic of time rupture in urban heritage, reflecting on time rupture on the protection and development of urban heritage and seeking new methods of urban weaving.
Time rupture is not a problem, it is a phenomenon, a description of the contradiction between urban heritage and modern urban environment. A rupture does not necessarily represent the obstacle, but provide new context of heritage conservation. According to the above analysis, this paper proposes three complementary suggestions for the protection of Shanghai's heritage: the first is to connect the urban heritage with the diverse forms of the past, the second is to complete the heritage narrative timeline whilst the third is to break the single image of urban heritage. Through the concept of time rupture, we can see the complexity of the problems facing the urban heritage and find necessary inspiration for further research.