Italy: Supper Hours Are Ending

Supper Hours Are Ending

The Last Supper, Leonardo da Vinci's masterwork, which is located in the former refectory of Milan's Santa Maria delle Grazie convent, was said to have begun deteriorating almost as soon as it was finished in 1497. The surface cracked because Da Vinci used an experimental primer on the wall. Then came the ravages of flooding, the cutting of a doorway, clumsy restoration and Allied bombing during World War II. But the latest attacks have come from modern tourists.

According to Italian restorers assessing the treasure with electronic microscopes, visitors track in urban dust and bacteria, and their rumbling tour buses spew...