Evaluation of the shelters over the prehistoric Megalithic Temples of Malta: environmental considerations

  • Francesca Becherini
  • JoAnn Cassar
  • Mario Galea
  • Adriana Bernardi
Original Article


Two of the seven prehistoric Megalithic Temples of the Maltese Islands inscribed on the UNESCO World Heritage List were covered by a temporary open-sided shelter in 2009. This was to protect the Temples from environmental factors, primarily direct rainfall and insolation, which were considered as main causes of deterioration of both the materials and the structures. The sheltering was preceded by intense environmental monitoring which lasted for 1 year and which was then partially continued even after the sheltering. This paper, evaluates the changes in environmental conditions both before and after sheltering and concludes that the advantages of the shelter far outweigh the disadvantages. Caution is, however, advocated in the case of noted disadvantages, such as salt, dust and pollution accumulation on the now protected megaliths, which should continue to be carefully monitored for any possible deleterious effects. Recommendations are also given for maintenance actions which can prevent these events from negatively affecting the state of conservation of the megaliths. These include the dry, soft regular brushing of the megaliths, and the surrounding ground, to remove accumulated salts which can cause the limestone to deteriorate if reabsorbed back into the porous stone either during RH fluctuations or on occasions when condensation events, which have been detected during the monitoring campaign even after the sheltering, occur.


Malta Megalithic Temples Shelters Limestone weathering Environmental monitoring Preventive conservation 



Authors wish to thank the Scientific Committee for the Conservation of the Megalithic Temples, Heritage Malta, Katya Stroud and Maria Elena Zammit. The authors gratefully acknowledge funding from 2006 EU Pre Accession Program/Transition Facility.


  1. Agnew N (2001) Methodology, conservation criteria and performance evaluation for archaeological site shelters. Conserv Manag Archaeol Sites 5:7–18CrossRefGoogle Scholar
  2. Agnew N, Neville H, Wade M (1986) A case study of a paleontological site—the need for planning and protection. In: Preventive measures during excavation and site protection, Ghent conference ICCROM proceedings, Rome, 6–8 November 1985, pp 257–270Google Scholar
  3. Agnew N, Maekawa S, Coffman R, Meyer J (1996) Evaluation of the performance of a lightweight modular site shelter: quantitative meteorological data and protective indices for the ‘hexashelter’. Conserv Manag Archaeol Sites 1(3):139–150CrossRefGoogle Scholar
  4. Aïcha BA, Demas M, Roby T (2008) Lessons learned: reflecting on the theory and practice of mosaic conservation. In: Proceedings of the 9th ICCM conference, Hammamet, Tunisia, 29 November–3 December 2005. Los Angeles, Getty Conservation InstituteGoogle Scholar
  5. Alef Y (2002) Evaluation of shelters over mosaics in Israel. Master’s thesis, Katholieke Universiteit, LeuvenGoogle Scholar
  6. Alef Y (2013) A guide to planning shelters over archaeological sites and over mosaics. Conservation Department, Heritage Conservation in Israel. Accessed 22/01/2016
  7. Architizer (2014) Indiana Jones meets ‘Alien’: these shelters bring Mayan ruins back to the future. Architizer Editors. Accessed 28/01/2016
  8. Ashurst J (2007) Conservation of ruins. Butterworth-Heinemann Series in Conservation and Museology, OxfordGoogle Scholar
  9. Avrami E, Barrow J, Jerome PR, Taylor MR (2002) Protective shelters for archaeological sites in the southwest USA. A colloquium held at Tumacacori, Arizona, 9–12 January 2001. In: Conserv Manag Archaeol Sites. Special issue on protective shelters 5(1–2): 3–6. doi: 10.1179/cma.2002.5.1-2.3
  10. Azlan Z (1997) Protective structures for the conservation and presentation of archaeological sites. J Conserv Mus Stud 3:16–20. doi: 10.5334/jcms.3974 CrossRefGoogle Scholar
  11. Bachmann M, Schwarting A (2008) Conservation projects in Pergamon. Building Z and the shelter constructed above it. Conserv Manag Archaeol Sites 10(2):157–173CrossRefGoogle Scholar
  12. Bernardi A (2008) Microclimate inside cultural heritage buildings. Il Prato, PadovaGoogle Scholar
  13. Bonazza A, Sabbioni C, Messina P, Guaraldi C, De Nuntiis P (2009) Climate change impact: mapping thermal stress on Carrara marble in Europe. Sci Total Environ 407:4506–4512CrossRefGoogle Scholar
  14. Bruno A (1987) Protecting and preserving the Column of Marcus Aurelius. Mus Int 39(1):3–7CrossRefGoogle Scholar
  15. Cabello Briones C (2013) A methodological approach to evaluation of shelter effectiveness for the conservation of archaeological sites. In: Rogerio-Candelera MA, Lazzari M, Cano E (eds) Science and technology for the conservation of cultural heritage. CRC Press, London, pp 41–44. ISBN 978-1-138-00009-4CrossRefGoogle Scholar
  16. Cassar J (2002) Deterioration of the Globigerina limestone of the Maltese Islands. In: Siegesmund S, Weiss T, Vollbrecht A (eds) Natural stone, weathering phenomena, conservation strategies and case studies. Geological Society, London, Special Publication 205, London, pp 33–49Google Scholar
  17. Cassar J, Tampone G, Vannucci S (1989) Conservazione e restauro dei templi megalitici preistorici maltesi: progetto bilaterale di ricerca e risultanze delle prime missioni di studio. In: Pre-prints of the 1st international symposium, the conservation of monuments in the Mediterranean Basin, pp 139–146Google Scholar
  18. Cassar J, Galea M, Grima R, Stroud K, Torpiano A (2011) Shelters over the Megalithic Temples of Malta: debate, design and implementation. Environ Earth Sci Spec Issue 63(7):1849–1860. doi: 10.1007/s12665-010-0735-8 CrossRefGoogle Scholar
  19. Cassar J, Cefai S, Galea M, Grima R, Stroud K, Torpiano A (2013) Preserving the Megalithic Temples of Malta-the interdisciplinary approach. Paper presented at the conference: built heritage. Monitoring Conservation Management, Milan, November 2013.
  20. Cerulli Irelli MG (1985) Il problema delle coperture dei complessi archeologici di Pompei ed Ercolano attraverso due secoli e mezzo di scavi. Restauro: Quaderni di restauro dei monumenti e di urbanistica dei centri antichi 14(81):7–11Google Scholar
  21. Chen J (1980) Xian: an archaeological site museum at Banpo. Museum 32(4):184–187Google Scholar
  22. Clemensen B (1992) Casa Grande Ruins National Monument, Arizona: a Centennial History of the First Prehistoric Reserve 1892–1992. Accessed 03/02/2016
  23. Cortes J (1989) Sistemas de Cobertura de mosaicos conservados in situ. I Coloquio Nacional de Conservacion de Mosaicos. Diputacion Provincial. Departamento de Cultura. Palencia, Spain, pp 143–149Google Scholar
  24. Cunliffe BW, Connor P, Pearson K (1968) Fishbourne: the Roman palace and its history. Sunday Times, LondonGoogle Scholar
  25. De Silva TKN (1986) Roof over a monument. Sri Lanka experience. In: Preventive measures during site excavation and site protection, Ghent conference ICCROM proceedings, Rome, 6–8 November 1985, pp 271–280Google Scholar
  26. Demas M (1990) Protective shelters. Preserving the archaeological record: post-excavation site conservation. MA thesis, Cornell UniversityGoogle Scholar
  27. Demas M (2002) Annotated bibliography on protective shelters for archaeological sites. Conserv Manag Archaeol Sites 5(1–2):91–105CrossRefGoogle Scholar
  28. Demas M (2003) The GCI project bibliographies series. Conservation and management of archaeological sites. The Getty Conservation institute, Los AngelesGoogle Scholar
  29. Doumas CG (2013) Managing the archaeological heritage: the case of Akrotiri, Thera (Santorini). Conserv Manag Archaeol Sites 15(1):109–120CrossRefGoogle Scholar
  30. EN16242:2012. Conservation of cultural heritage. Procedures and instruments for measuring humidity in the air and moisture exchanges between air and cultural propertyGoogle Scholar
  31. Ertosun AI (2012) Evaluation of protective structures in archaeological sites for in situ conservation of architectural remains and artifacts. Dissertation, Middle East Technical UniversityGoogle Scholar
  32. Farrugia S, Schembri JA (2008–2009) Wind funneling underneath the Hagar Qim protective shelter. Malta Archaeol Rev 9: 51–59Google Scholar
  33. Federico LI (1985) Protective coverings for archaeological sites: the case of Pompeii. ICOMOS Inf 4:7–12Google Scholar
  34. Feilden Clegg Bradley (2015) Feilden Clegg Bradley studios designs larch-clad shelter for Roman ruins. de zeen magazine. Accessed 16/02/2016
  35. Fentress E (2001) Protective shelters for archaeological areas and buildings A one-day conference held at the Museo Civico Archeologico di Bologna, October 2000. Conserv Manag Archaeol Sites 5(1&2):106–108Google Scholar
  36. Fiandra E (1960) A museum amid the ruins of a Minoan villa. Museum 13(2):130–132Google Scholar
  37. Fintikakis N, Doumas C (2014) Enhancement, presentation and shelter replacement of the archaeological site at Akrotiri, Thera. In: Project Baikal 42. doi: 10.7480/projectbaikal.42.802
  38. Fitch JM (1982) Protection and interpretation of sites and ruins. In: Historic preservation: curatorial management of the built world. McGraw-Hill, Charlottesville, pp 293–306Google Scholar
  39. Flatt RJ, Caruso F, Aguilar Sanchez AM, Scherer GW (2014) Chemo-mechanics of salt damage in stone. Nat Commun. doi: 10.1038/ncomms5823 Google Scholar
  40. Franciosi R (2014) Architecture × archaeology. Domus. Accessed 10/02/2016
  41. Galdies C (2011) The climate of Malta: statistics, trends and analysis 1951–2010, National Statistics Office Malta. Accessed 20/02/2016
  42. Galea M, De Battista R, Grima M, Maccarelli L, Borg R, Zerafa C (2016) Pollution monitoring for sea salt aerosols and other anionic species at Hagar Qim temples Malta—a pilot study. Conserv Manag Archaeol Sites. doi: 10.1080/13505033.2016.1191890
  43. GCI (2014a) Shelters for archaeological sites with mosaics: protective shelters for archaeological sites. Mosaikon. Accessed 05/02/2016
  44. GCI (2014b) Shelters for archaeological sites with mosaics: developing guidelines for archaeological shelters. Mosaikon. Accessed 05/02/2016
  45. Hinkel F (1968) Progress report on the removal of endangered monuments from Sudanese Nubia. Kush. J Sudan Antiq Serv 16:79–84Google Scholar
  46. Hu J (1986) A museum on the site of an ancient copper mine. Museum 38(2):115–119Google Scholar
  47. Jerome P, Taylor MR, Montgomery J (2001) Evaluation of the protective shelter at Blackwater Draw Archaeological Site, New Mexico. Conserv Manag Archaeol Sites 5(1&2):63–72Google Scholar
  48. Laurenti MC, Prosperi Porta C (2006) Realizzazione di un prototipo di copertura protettiva. In: Laurenti MC (ed) Le coperture delle aree archeologiche: Museo aperto. Gangemi Editore, Roma, pp 271–278Google Scholar
  49. Lewis H (1980) Experiments in mudbrick conservation at Tepe Nush-I Jan. In: Üçüncü Uluslararası Kerpiç Koruma Sempozyumu: 29 Eylül-4 Ekim, 1980, Ankara = Third International Symposium on Mudbrick (Adobe) Preservation: 29 September-4 October 1980, Ankara, 109–118. ICOMOS/ICOM, Ankara.
  50. Llop E, Alvaro I, Hernandez Marine M, Sammut S, Gómez Bolea A (2013) Biological crusts contribute to the protection of Neolithic Heritage in the Mediterranean region. In: Rogerio-Candelera MA, Lazzari M, Cano E (eds) Science and technology for the conservation of cultural heritage. Taylor and Francis Group, LondonGoogle Scholar
  51. Masera G, Imperadori M, Vanossi A, Liotta SJ, Ito Y (2015) Modular, adaptable shelters for environmentally sensitive archaeological sites. In: Proceedings of the international association for shell and spatial structures IASS WG12 + WG18, joint international colloquium on bio-based and bio-inspired environmentally compatible structures, Tokyo, Japan, 11–12 April 2015, Tokyo Denki UniversityGoogle Scholar
  52. Michaelides D (2003) Mosaics make a site: the conservation in situ of mosaics on archaeological sites. In: Michaelides D (ed) Proceedings of the VIth conference of the international committee for the conservation of mosaics, Nicosia, Cyprus, August 1996. Published in Rome by ICCM, Getty Conservation Institute, ICCROMGoogle Scholar
  53. Minissi F (1961) Protection of the mosaic pavements of the Roman villa at Piazza Armerina (Sicily). Museum 14:128–132Google Scholar
  54. Neguer J (2004) Reburial and protective covering of ancient mosaic pavements: the experience of the conservation department of the Israel Antiquities Authority. Conserv Manag Archaeol Sites 6(3&4):247–258CrossRefGoogle Scholar
  55. Neguer J, Alef Y (2008) Rapid assessment of shelters over mosaics: methodology and initial results from England 181. In: Abed AB, Martha Demas M, Roby T (eds) Lessons learned: reflecting on the theory and practice of mosaic conservation: proceedings of the 9th ICCM conference, Hammamet, Tunisia, November 29–December 3 2005, Getty Conservation InstituteGoogle Scholar
  56. Pesaresi P, Rizzi G (2007) New and existing forms of protective shelter at Herculaneum: towards improving the continuous care of the site. Conserv Manag Archaeol Sites 8(4):237–252CrossRefGoogle Scholar
  57. Rizzi G (2008) Sheltering the mosaics of Piazza Armerina: issues of conservation and presentation. Archaeological Institute of America.
  58. Rothert E, Eggers T, Cassar J, Ruedrich J, Fitzner B, Siegesmund S (2007) Stone properties and weathering induced by salt crystallization of Maltese Globigerina Limestone. In: Prikryl R, Smith BJ (eds) Building stone decay: from diagnosis to conservation. Geological Society, London, Special Publications, 271, London, pp 189–198Google Scholar
  59. Ruedrich J, Siegesmund S (2007) Salt and ice crystallization in porous sandstones. In: Environmental geology, March 2007, volume 52, issue 2, pp 225–249. First online 19 December 2006Google Scholar
  60. Ruedrich J, Rieffel Y, Pirskawetz S, Alpermann H, Joksch U, Gengnagel C, Weise F, Plagge R, Zhao J, Siegesmund S (2010) Development and assessment of protective winter covers for marble statuaries of the Schlossbrücke, Berlin (Germany). In: Environmental earth science, special issue, August 2011, volume 63, Issue 7, pp 1823–1848. First online 19 October 2010. doi: 10.1007/s12665-010-0765-2
  61. Sabbioni C (2003) Mechanisms of air pollution damage to stone. In: Brimblecombe P (ed) The effects of air pollution on the built environment. Imperial College Press, London, pp 63–106CrossRefGoogle Scholar
  62. Stanley Price N, Jokilehto J (2001) The decision to shelter archaeological sites: three case-studies from Sicily. Conserv Manag Archaeol Sites 5(1&2):19–34Google Scholar
  63. Stanley Price N, Ponti G (2003) Protective enclosures for mosaic floors: a review of Piazza Armerina, Sicily, after forty years. In: Michaelides D (ed) Proceedings of the VI conference of the international committee for the conservation of mosaics, Nicosia, Cyprus, August 1996. Published in Rome by ICCM, Getty Conservation Institute, ICCROMGoogle Scholar
  64. Tampone G, Vannucci S, Cassar J (1991) Aspetti architettonici e costruttivi dei templi megalitici preistorici maltesi e criteri di restauro. In: La preistoria de les illes de la Mediterrania occidental, X Jornades d’Estudis Historics Locals, Mallorca, Spain, pp 243–276Google Scholar
  65. Tampone G, Vannucci S, Cassar J, Ferri W, Fiorito P, Pieri-Nerli P, Sausa P, Zetti I (1994) I templi megalitici preistorici delle isole maltesi: la rilevazione architettonica. In: Proceedings of the 3rd international symposium, the conservation of monuments in the Mediterranean Basin, Venice, Italy, pp 443–453Google Scholar
  66. Torpiano A (2004) The construction of the prehistoric Megalithic Temples of Malta. In: Cilia D (ed) Malta before history. Miranda Publishers, Malta, pp 347–365Google Scholar
  67. Vasić-Petrović E, Momčilović-Petronijević A (2015) Shelters for archaeological sites in Serbia: a research aiming to develop guidelines for future design and construction. Facta Univ Ser Archit Civ Eng 13(2):113–121CrossRefGoogle Scholar
  68. Vergès-Belmin V (ed) (2008) Illustrated glossary on stone deterioration patterns = Glossaire illustré sur les forms d’altération de la pierre. English-French ed. Monuments and Sites 15. Paris: ICOMOS (International Council on Monuments and Sites) and ISCS (International Scientific Committee for Stone).
  69. Weaver M (1973) The use of an inflatable “air-dome” to produce controlled conditions for an archaeological site. Stud Conserv 18(2):88–93Google Scholar
  70. Zanelli A, Rosina E, Maffei R, Carra G, Beccarelli P (2013) Innovative solutions for ultra-lightweight textile shelters covering archaeological sites. In: Cruz PJS (ed) Structures and architecture new concepts, applications and challenges. CRC Press, Taylor&Francis Group, London, pp 1326–1333CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Francesca Becherini
    • 1
  • JoAnn Cassar
    • 2
  • Mario Galea
    • 3
  • Adriana Bernardi
    • 1
  1. 1.Institute of Atmospheric Sciences and ClimateNational Research CouncilPaduaItaly
  2. 2.Department of Conservation and Built Heritage, Faculty for the Built EnvironmentUniversity of MaltaMsidaMalta
  3. 3.Preventive Conservation UnitHeritage MaltaKalkaraMalta

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