The Arno is the most important river of central Italy after the Tiber. The Arno river originates on Mount Falterona on the Apennines, runs near Arezzo passing through Florence, Empoli and Pisa, and flows into the Tyrrhenian Sea, after a journey of 241 kilometers. It crosses Florence, where it passes below the Ponte Vecchio and the Santa Trìnita bridge, inspired by Michelangelo. The river flooded this city regularly in historical times, the last occasion being the famous flood of November 4, 1966, when it collapsed the embankment in Florence, damaging or destroying millions of works of art and rare books. New conservation techniques were inspired by the disaster, but even 40 years later hundreds of works still await restoration.