Lake Bracciano (Italian: Lago di Bracciano) is a lake of volcanic origin in the Italian region of Lazio, 32 km (20 mi) northwest of Rome. It is the second largest lake in the region (second only to Lake Bolsena) and one of the major lakes of Italy. It has a circular perimeter of approximately 32 km (20 mi). Its inflow is from precipitation runoff and percolation, and from underground springs, and its outflow is the Arrone. Three towns border the lake, Bracciano, Anguillara Sabazia and Trevignano Romano.