On November 4, 1966, Florence, one of the world’s most historic cities and the repository of perhaps its greatest art, was struck by a monumental calamity. A low-pressure system had been stalled over Italy for six weeks and on the previous day it had begun to rain again. Nineteen inches fell in twenty-four hours, more than half of the annual total. By two o’clock in the morning twenty-thousand cubic feet of water per second was moving towards Florence. Soon manhole covers in Santa Croce were exploding into the air as jets of water began shooting out of the now overwhelmed sewer system. Cellars, vaults, and strong-rooms were filling with water. Night watchmen on the Ponte Vecchio alerted the bridge’s jewelers and goldsmiths to come quickly to rescue their wares. By then the water was moving at forty miles per hour at a height of twenty-four feet. At 7:26 a.m. all of Florence’s electric civic clocks came to a stop. The Piazza Santa Croce was under twenty-two feet of water. Beneath the surface, twelve feet of mud, sewage, debris, and oil sludge were starting to ooze and settle into the cellars and crypts and room after room above them. Six-hundred-thousand tons of it would smother, clot, and encrust the city.