Trevi nel Lazio is located in the centre of a wide valley in the Cantari mountains, through which the Aniene river flows, but which is now dammed to form a reservoir for the production of hydroelectric power.
Trevi derives its name from the term treba (crossroads) describing its position on three roads. In addition it was always an important animal breeding center since Roman times. The community was never prosperous since most of the population was forced to move seasonally, to the Pontine and Roman plains in winter along with their stock.
Trevi was under the protection of the Caetani but persistent feudal misrule resulted in the Caetani being expelled in 1471 and Trevi fell into the area of the Subiaco monks.