TODAY IN ITALY, THE SCENIC Serchio River winds its way for nearly 80 miles through lush Tuscan countryside. Stretches of the river are popular for whitewater rafting, but the modern Serchio is not a particularly dangerous or destructive river. Long ago, however, it raged.

During the sixth century, the river frequently flooded the town of Lucca, which sits on a floodplain in its path. According to a local legend that persists today, Lucca was saved by St. Fridianus, an Irish pilgrim who had relocated to Tuscany, where he became a bishop known today as San Frediano.