Avernus was an ancient name for a volcanic crater near Cumae (Cuma), Italy, in the Region of Campania west of Naples. Part of the Phlegraean Fields of volcanoes, Avernus is approximately 3.2 kilometres (2.0 mi) in circumference. Within the crater is Lake Avernus (Lago d'Averno). Avernus was believed to be the entrance to the underworld, and is portrayed as such in the Aeneid of Virgil. The name comes from the Greek word aornos (ἄορνος < a- ‘no’ + ornis ‘bird’), meaning "without birds", because ...