During the Sack of Rome (1527), Clement VII (1523–1534) took refuge at Orvieto. Preparing for a possible siege of the city, he ordered the "Pozzo di S. Patrizio" ("Well of St. Patrick) constructed by architect-engineer Antonio da Sangallo the Younger. Of course, the pope and emperor had reconciled long before the well was completed. Sixtus V (1585–1590) drained the swamps around the city.