A larger excavation in the side of the hill facing the sea, with a flight of steps leading up from it into another smaller recess, and numerous lateral openings and subterranean passages, supposed to penetrate into the very heart of the mountain, and even to communicate with Lake Fusaro, is pointed out by the local guides as the Sibyl's Cave, which, as Virgil tells us, had a hundred entrances and issues, from whence as many resounding voices echoed forth the oracles of the inspired priestess.
Source: tatoeba (11056814)