Why The Last Supper Is Falling Apart

Leonardo da Vinci's The Last Supper is not a fresco. A true fresco is painted directly onto wet plaster, which bonds the pigment to the wall as both dry — permanent, but requiring the painter to work extremely fast. Leonardo instead painted in tempera and oil on a dry plaster surface, using an experimental technique that gave him the slow, deliberate pace he preferred. The problem is that this method doesn't bond to the wall the same way. The paint started flaking almost immediately after the work was finished in 1498, and the painting has been deteriorating ever since. Every subsequent attempt to save it — including a botched 18th-century restoration and a bombing that destroyed the refectory roof in 1943 — made things worse. The restoration completed in 1999 stabilized what remains, but roughly 80 percent of the original surface is now lost. What you're seeing is largely the work of centuries of restorers rather than Leonardo himself.

The Navigli canal district has a less visible connection to Leonardo. The vast network of navigli — canals — that once crisscrossed Milan was the logistical spine of the Duomo's construction — marble quarried near Lake Maggiore was floated down to the city via canals. Leonardo, living in Milan under the patronage of Ludovico Sforza, worked on improvements to the canal lock system in the 1490s. Most of the city's canals were filled in during the 1930s under Mussolini, leaving only the Naviglio Grande and Naviglio Pavese. The rest are now streets, with the old canal beds still visible as unusually wide, slightly sunken roads in the urban grid.