Conservation work under the Great Pompeii Project began at the site in 2013. Credit: Circo de Luca/Reuters/Corbis

Ancient Pompeii, which suffered three wall collapses this month, may look to its smaller sister city Herculaneum for tips to ensure its survival. Both cities, located on Italy’s Neapolitan coast, were simultaneously destroyed and preserved by the eruption of Mount Vesuvius in ad 79, but the historic site of Herculaneum is faring much better, thanks to a sustainable conservation project.

Now an international research consortium is planning a similar pilot scheme for Pompeii. And researchers and officials are hoping that a €105-million (US$145-million) European Union project to restore Pompeii will also draw on lessons from Herculaneum. The rescue plan cannot come soon enough. “A lot of buildings are at risk [of collapse],” one anonymous observer close to the restoration efforts told Nature, adding that, as well as the repair effort, “they need a system to maintain the site so that it doesn’t happen again”. Excavations of Pompeii, which, with Herculaneum, is a World Heritage Site of the United Nations Educational, Scientific and Cultural Organization, began in the mid-eighteenth century. But conservation took off only in the early twentieth century, by which time much of the city had been reduced to walls. However, decay at the 66-hectare site has accelerated since the 1960s as a result of haphazard funding and the disbanding of in-house maintenance crews. This month’s collapses are the latest in a series of incidents since the 1980s. Water is the site’s biggest enemy: unexcavated embankments absorb rainfall and exert pressure on adjoining structures, and poor drainage allows surface water to accumulate. A lack of regular repair work means that rain also seeps into the walls. Much of Pompeii’s masonry consists of rubble stonework, which is highly vulnerable. Typically, this consists of two wall coverings assembled with roughly placed stones of volcanic tuff (opus incertum), together with a core of smaller stones set in a lime-mortar grout (opus caementicium). Such constructions show excellent longevity if kept dry. But water infiltration has led to repeated wetting and drying, causing stones to chip and flake, and the mortar to decay and lose cohesion. In addition, many twentieth-century conservation interventions at Pompeii have since proved inappropriate and damaging. The authorities are responding, however. In February 2013, the European Union and the Italian government launched an emergency €105-million project to reverse the decades of neglect. Dubbed the Great Pompeii Project, it focuses on draining and securing embankments, restoring masonry and decorated surfaces, and protecting buildings from weathering. But the project, the budget for which must be spent by the end of 2015, has been beleaguered by concerns that delays and bureaucracy may affect the quality of the work. In response, the European Commission said on 6 March that it will carry out an urgent public review of progress. Johannes Hahn, the European commissioner for regional policy, says that the review’s aim is clear. “We have professionals working on the site. The most helpful thing we can do for them is to remove the bureaucratic barriers and let them get down to work.” Massimo Osanna, appointed this month as head of the Special Superintendency for the Archaeological Heritage of Naples and Pompeii, which is in charge of the site’s conservation, says that although a longer time frame would be preferable, criticism of the pace of progress is unfair. High-quality archaeological conservation of an open-air site as vast as Pompeii inevitably has long lead times, he argues, and plans for using the money are already well under way. Having a proper plan for the sustainable management of Pompeii is also a major issue. The outsourcing of routine maintenance to contractors since the 1980s has had severe effects, with repeated delays to urgent repairs, says Andrew Wallace-Hadrill, a social and cultural historian at the University of Cambridge, UK. Wallace-Hadrill heads what many see as a model for conserving Pompeii: the Herculaneum Conservation Project (HCP). This was launched in 2001, when Herculaneum was in a dire state, as a public–private venture between the philanthropic Packard Humanities Institute of Los Altos, California, the British School at Rome and the superintendency. In just over a decade, and having spent €20 million in total, it has helped to reverse the decay and put the town on a sustainable conservation footing (see ‘Under a shadow’). “I’m impressed; Herculaneum was a very sad, dirty and abandoned place; now it’s fantastic,” says Albrecht Matthaei, an archaeologist at the Roma Tre University. Although under the jurisdiction of the superintendency, the HCP’s level of autonomy frees it from state bureaucracy, notes Wallace-Hadrill. The HCP also brings together archaeologists, engineers and other scientists with conservators. This, together with an emphasis on routine maintenance, has been key, says Wallace-Hadrill. And the project differs from the typical conservation practice of carrying out complete restorations on a house-by-house basis by focusing on urgent site-wide restorations and repairs. Now, a proposed project, the Pompeii Sustainable Preservation Project (PSPP), is taking inspiration from the HCP. An international consortium of research institutions, including the Fraunhofer research organization and the Technical University of Munich in Germany, hopes to raise US$10 million in philanthropic funding to launch a ten-year pilot project later this year that will study long-term, sustainable conservation and restoration approaches at Pompeii. “HCP is best practice,” says Matthaei, a coordinator of the PSPP. The new project seems laudable, but until work begins it is difficult to assess, adds Wallace-Hadrill.

Osanna says that Pompeii’s greater size makes comparisons with the HCP difficult. But he is confident that the Great Pompeii Project can fix the city. “People need to give the project time to get up to speed, after which any controversy will hopefully be put to rest,” he says.