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TOWER OF BELÉM
Preserving a symbol of Lisbon's golden age of exploration
At the end of the 15th century, King D. João II of Portugal commissioned the Tower of Belém as part of a tripartite defensive network to protect the port of Lisbon. Originally, a man-of-war called the Grande Nau, or big vessel, guarded the estuary where the Tagus River flowed into Lisbon harbor until it was decided one of these new fortresses would replace it. When construction began under Manuel I, the king's successor, the foundations of the fortress were built on the same basalt outcropping the Grande Nau used as its mooring. Between 1514-1519, as the tower and its hull-shaped bastion below were fully realized in cream-colored Lioz limestone, the fortress came to resemble a galleon petrified in stone. At the time, Belem had become a vital launching point for Portuguese exploration abroad and this is reflected in the Manueline tower's design. From its naval-inspired exterior motifs to the vented casemate, which was designed to accommodate the new developments in 16th century artillery that helped to solidify Portugal's maritime empire, the tower's architecture crystallizes an age in which Portugal became the first commercial and maritime empire in early modern Europe.
HOW WE HELPED
In May 1994, WMF compiled a survey report on the state of conservation at the Tower of Belém, which systematically identified and mapped deterioration and alterations found on each stone. From February to August 1997, conservators then focused on the tower and from September 1997 to February 1998, the team addressed the bulwark. Conservators worked to clean biological colonization and black crusts from stone surfaces and re-attach loose architectural elements using a variety of methods. A water-repellant treatment was applied to the exterior surfaces that were most exposed to rain. The final step of the project was the documentation of the different interventions, which were then inserted into a database created at the beginning of the project. Efforts to improve site access and presentation were also made during the project.
WHY IT MATTERS
Though the tower was stable, other problems had developed over time due to air pollution and weathering caused by the harbor winds. The architectural sculptures at the base of the turrets displayed severe deterioration as a result of their exposed position. The outer stone surfaces of the tower were in a stable condition but required cleaning to remove lichen and black crusts caused by air pollution. The most crucial conservation issues at the Tower of Belém concerned water ingress. The Lioz limestone is comprised of calcium carbonate, which causes it to be vulnerable to erosion by acidic agents like acid rain. This process had further affected the carved details decorating the tower. In reaction to these issues, Isabel Cruz de Almeida, Director of the Tower of Belém and Jerónimos Museum at the time, stated, “It is now a cultural beacon, an icon reminding the Portuguese people and visitors from abroad of the country's rich and exciting heritage.” She added, “What would the message be to the people of Portugal, if that icon were allowed to deteriorate?”
Read Conservation of Architectural Heritage in Portugal towards the end of the 20th Century. Is it valid to consider a "WMF" effect? (PDF, in Portuguese, with English summary), as presented at Simpósio Património em Construção: Contextos para a sua preservação in November of 2011.