San Pietro extra moenia stands below the town walls, accessible by the road south of the Ponte delle Torri or by the path through the gorge. The church's exterior is its great treasure: a 12th-century Romanesque facade covered in sculpted reliefs depicting scenes from the life of Saint Peter alongside allegorical and moral tales — lions, deer, serpents, monks, and eagles carved with a directness and energy that later Gothic and Renaissance sculpture sometimes lost.
Founded in the 5th century to house what were believed to be the chains of Saint Peter, the church was rebuilt in the 12th and 13th centuries. The carved decorations include one of the oldest depictions of a cat in Italian medieval art — spotting it is a small reward for reading the facade carefully. The interior is simpler than the exterior suggests, but the walk to get here, along the gorge from the Ponte delle Torri, is worth the trip in itself.