Castel Viscardo is a comune (municipality) in the Province of Terni in the Italian region Umbria, The town lies about 60 km southwest of Perugia and about 35 km northeast of Terni.

Monterubiaglio is a paesello, a small hilltop village, below Castel Viscardo.

Monterubiaglio has approximately 600 inhabitants, but during the summer time the population grows much larger as it is a popular vacation spot for persons who are originally from the village but may have moved elsewhere such as Rome.

Since 2006, the Department of Classics at Saint Anselm College has been excavating an Etrusco-Romano site just below Monterubiaglio.

The excavation has yielded a number of finds and structures that date from the 8th century BCE to the 10th CE.