The Necromanteion is sited at the top of a hill near the village of Mesopotamos, where the rivers of Hades-Acheron and Kokytos-converge on the north-west shore of Acherousia Lake. The lake was drained in the 20th century. The ancients would go to the Necromanteion to contact the souls of the dead would foretell their future. It was a maze of dark corridors and rooms for ceremonies and visitor accommodation. The underground crypt is where the encounters with the “shadows” of the dead took place. The ceiling was supported by 15 carved stone arches.