Wikipedia
Aornum
Aornum ( Ancient Greek: ) was an oracle in Ancient Greece, located in Thesprotia in a cave called Charonium which gave forth poisonous vapours. The name of the cave, " Charon's Cave", reflects the belief that it was an entrance for Hades, the Greek underworld. In a version of the myth, Orpheus travels to Aornum to recover his wife, Eurydice, from Hades.