Castel Giorgio is a comune (municipality) in the Province of Terni in the Italian region Umbria, located about 60 kilometres (37 mi) southwest of Perugia and about 60 km northwest of Terni on the Alfine Highland, facing the Lake Bolsena.

In 1993, remains from prehistoric Villanovan civilization settlements were found in the area of Castel Giorgio.

Also present are an Etruscan necropolis (3rd-2nd centuries BC) and remains of Roman villas and roads (Via Traiana Nova and Via Cassia).

The town was founded in 1477, as castle and residence for the bishop of Orvieto, Giorgio della Rovere.

After several vicissitudes, the palace was restored by Cardinal Giacomo Sannesio in 1610–1620, turning it into a summer resort for the prelates of Orvieto.