As the most famous St. Patrick's Well, it is carved into the stone, and has a depth of 36 meters. The floor is covered with mud and clay and is equipped with a groove. When, in 1527, Pope Clement VII ordered the excavation of the St. Patrick's Well, did this also readjust structure of this of Etruscan origin. One legend has it that the Well was closed because there were sown five French officers who had used violence against women in the neighborhood. Between 1985 and 2004 it has been rediscovered the caves around. The Well is located in an underground complex of nine adjoining rooms, rich in archaeological Etruscan, medieval and Renaissance remains. The Medieval furnace is on the ground, and kept the remains of the furnace and fragments of earthenware, tools for shaping and decorating pottery. The large pillar in the center is the rest of a Medieval tower built by the Simon Filippeschi's sons. The last cave of the path, discovered in 2002, are still the subject of debate: some have suggested it is stable, those of a necropolis, a tanker who never completed. Every year, at Christmas time, the Well becomes the scene of a nativity with life-size animated characters.