The ancient Greeks believed that a cave in the ancient city of Hierapolis was the “gate to hell”. Known as Pluto’s Gate (Plutonium) was believed to be the portal to the underworld.
The opening of the cave was filled with lethal mephitic vapors as described by the Greek geographer and historian Strabo (circa 64 BC – circa 24 AD):
“This space is full of a vapor so misty and dense that one can scarcely see the ground. Any animal that passes inside meets instant death. I threw in sparrows and they immediately breathed their last and fell.”
Only the eunuchs of Cybele, an ancient fertility goddess, were able to enter the Pluto’s Gate without any apparent damage, since (according to Strabo) “They hold their breath as much as they can."
He goes on to notice that their immunity could have been due to their "menomation" (impairment), “divine providence” or “certain physical powers that are antidotes against the vapor.”
Classic archeology Professor Francesco D’Andira and his team were excavating the Hellenistic city of Hierapolis in Pamukkale, Turkey, when they found Ionic semi columns and, on top of them, an inscription with a dedication to the deities of the underworld Pluto and Kore. The temple remains, pool and a series of steps placed above the cave were all as described in ancient sources.
The bustling city of Hierapolis at the time had temples, a theater and popular sacred hot springs, believed to have healing properties. It seems that the site was managed at the time by a tourist organization. Pilgrims received (quite likely against a fee) small birds to check out the deadly workings of Pluto’s Gate (not unlike coal mine canaries). They would take the waters in the pool near the temple, sleep close to the cave and would promptly experience visions and receive prophecies (the Oracle of Delphi effect).
According to the Professor, “We could see the cave's lethal properties during the excavation. Several birds died as they tried to get close to the warm opening, instantly killed by the carbon dioxide fumes.”
So the next time you tell somebody to go to hell, they might send you a postcard from Turkey!