Pozzo di San Patrizio, or the Well of Saint Patrick, is a historic well located in the town of Orvieto, in the Umbria region of Italy. The well was built in the 16th century by Pope Clement VII to ensure that the town would have a reliable source of water during a siege.

The well is 62 meters deep, and has two spiral staircases with 248 steps leading down to the water at the bottom. The design of the well allowed for mules to travel down one staircase to the water, while carrying empty water vessels, and then back up the other staircase carrying full water vessels, without interfering with each other.

The well is an impressive feat of engineering and architecture, with its double helix design and ventilation shafts providing both beauty and functionality. Visitors can climb down the staircases to see the water at the bottom, and also enjoy the cool air provided by the ventilation shafts.

Today, the Pozzo di San Patrizio is a popular tourist attraction and a testament to the ingenuity of Renaissance engineering.