Albano, Lake (älbäˈnō) [key], crater lake, 2 sq mi (5.2 sq km), central Italy, in the Alban Hills SE of Rome. It is c.6 mi (9.7 km) in circumference and c.560 ft (170 m) deep. An underground tunnel built in the 4th cent. B.C. is still its only outlet. Alba Longa was located near the lake. Castel Gandolfo, the Pope's summer residence, is located there. South of the lake is Albano Laziale, a small town on the Appian Way, noted for the beautiful villas and several tombs built there by the ancient Romans.