Encyclopædia Britannica, Ninth Edition/Avernus
AVERNUS, a lake of Campania in Italy, near Baiae, occupying the crater of an extinct volcano, and about a mile and a half in circumference. From the gloomy horror of its surroundings, and the mephitic character of its exhala tions, it was regarded by ancient superstition as an entrance to the infernal regions. It was especially dedicated to Proserpine, and an oracle was maintained on the spot. In 214 B.C., Hannibal with his army visited the shrine, but not so much, according to Pliny, for purposes of piety, as in hope of surprising the garrison of Puteoli. By some critics the Cimmerians of Homer were supposed to have been the inhabitants of this locality, and Virgil in his ^Eneid adopted the popular opinions in regard to it. Originally there seems to have been no outlet to the lake, but Agrippa opened a passage to the Lucrine, and turned this " mouth of hell " into a harbour for ships. The channel, however, appears to have become obstructed at a later period. In the reign of Nero it was proposed to construct a ship-canal from the Tiber through Avernus to the Gulf of Baise, but the works were hardly commenced. The plan of connecting the lake with the Gulf of Baiaa was brought forward as late as 1858, but only to be abandoned. The Lago d Averno is now greatly frequented by foreign tourists, who are shown what pass for the Sibyl s Grotto, the Sibyl s Bath, and the entrance to the infernal regions, as well as the tunnel from Cumae, and ruins variously identified as belonging to a temple or a batliing-p .ace.