in the Philippines' Tentative List for possible designation as a World Heritage Site, on account of its architectural and historical heritage. the church is no longer included in the Tentative List. Preservation In recent years, San Sebastian Church has encountered threats to its structural integrity. The steel structure has been beset by rust and corrosion due to sea breezes from nearby Manila Bay. State funding was accorded to the church through the National Historical Institute which undertook restoration in 1982. The Recollect community has likewise expended funds for the church's maintenance and restoration. In 1998, it was placed on the biennial watchlist of the 100 Most Endangered Sites by the World Monuments Fund, though it was not retained in the subsequent watchlists. The church was listed again as one of the most endangered monuments in the world by World Monuments Fund in the 2010 World Monuments Watch, along with the Rice Terraces of the Philippine Cordilleras and Santa Maria Church. All of the sites were taken off the list in 2011 after the passage of the National Cultural Heritage Act. UNESCO re-inclusion troubled On October 1, 2018, it was revealed that a thirty one-storey residential highrise building of Summithome Realty Corporation is being planned to be constructed beside the historic San Sebastian Church, negatively affecting the site's possible re-inclusion in the UNESCO tentative list as the area around the church is integral to the site as a 'buffer zone'. The site, the first and only all-steel church in Asia, used to be in the UNESCO tentative list but was removed in 2015 due to structural decay. To re-establish the site's integrity and re-inclusion in the tentative list, it underwent a massive restoration program, which conservationists have cited as a megalithic success. However, with the looming threat of the high-rise building, the site's inclusion in the UNESCO list is bleak. Summithome was able to acquire a barangay clearance supporting their application for a building permit from the barangay chairman, without the site managers being initially informed. Alleged involvement of Gustave Eiffel It has long been reputed that Gustave Eiffel, the French engineer behind the Eiffel Tower and the steel structure within the Statue of Liberty, was involved in the design and construction of San Sebastián, but this was never confirmed. However, it was confirmed later on that Eiffel was involved in designing and supplying the metal framework for San Ignacio Church