The Pozzo di San Patrizio (English: “St. Patrick’s Well”) was built by 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 and who feared 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.  The name was inspired by medieval legends that St. Patrick’s Purgatory in Ireland gave access to Purgatory, indicating something very deep.  Da Sangallo surrounded the central well shaft with two helical ramps in a double helix, accessed by two doors, which allowed mules to carry empty and full water vessels separately downward and upward without obstruction. The well is 53.15 metres (174.4 ft) deep with a base diameter of 13 metres (43 ft), with 248 steps and 70 windows providing illumination.  That’s a lot of explanation, but the unused card itself is also detailed.  Grade: 1