San Pietro in Valle, Medieval abbey in Ferentillo, Italy.

San Pietro in Valle is a monastery complex in Ferentillo, Umbria, at about 370 m above sea level. Its church, a separate body from the abbey, has a single nave dating to the 7th century and a 12th-century apse. The abbey buildings include a tall square bell tower in pale stone with tall arched openings near the top, and a small round apse with a conical roof.

Faroaldo II, Duke of Spoleto, founded the monastery in the 8th century after, according to legend, Saint Peter appeared to him in a dream. He later gave up his title and became a monk there. In 996 Otto III revived the abbey after a Saracen sack, and in 1234 Gregory IX assigned it to the Cistercians.

The nave walls carry a Roman-school fresco cycle of the Old and New Testaments painted around 1150, before the work of Pietro Cavallini. In the apse, frescoes of 1445 are attributed to the Master of Eggi. The main altar's two bas-relief slabs are Lombard: a Latin inscription names Duke Ilderico of Spoleto (739–742) and the sculptor, signed Ursus magester fecit.

The former monastery buildings are private property and now house a hotel, while the church belongs to the curia. The abbey stands at about 370 m above sea level in the municipality of Ferentillo, in the Valnerina. The church reopened on 11 April 2026 after restoration work begun in 2023, with a new lighting system.

Four 2nd-century Roman sarcophagi stand in the church, carved with scenes of three boats bound for Hades, Dionysus with Silenus, Pan and a dancing maenad, Cupid and Psyche, and hunters. Their style points to eastern workshops. A carved slab known as the Bear carries the signature Ursus magester fecit, naming the sculptor.