The Pozzo di San Patrizio (English: "St. Patrick's Well") is a historic well in Orvieto, Umbria, central Italy. It was built by architect-engineer Antonio da Sangallo the Younger of Florence, between 1527 and 1537, at the behest of Pope Clement VII who had taken refuge at Orvieto during the sack of Rome in 1527 by the Holy Roman Emperor Charles V, and feared that the city's water supply would be insufficient in the event of a siege. The well was completed in 1537 during the papacy of Pope Paul III.