Albanus lacus (mod. Lago Albano), ‘Alban Lake’, a crater lake in the *Albanus mons near Rome. Its wooded banks in imperial times were studded with *villas, e.g. *Domitian's. Lacking natural outlets, its waters reach the Rivus Albanus, and thence the Tiber, via a tunnel, 1,800 m. (1,968 yds.) in length, through the crater rim built c.