circular lake in Roma provincia, Lazio (Latium) regione, central Italy. It lies in the Sabatini Mountains, just northwest of Rome. Mineral hot springs along its shores recall its earlier geologic formation from a group of volcanic craters. The surface lies 538 feet (164 m) above sea level, with an area of 22 square miles (58 square km). The maximum depth is 525 feet (160 m) and the diameter is about 5.5 miles (9 km). The lake, drained by the Arrone River on its southeast side, is known for its eels and other fish. The lakeside towns of Bracciano and Anguillara Sabazia preserve their magnificent late-medieval castles. There is a museum of military airplanes at Vigna di Valle on the south shore.