a statue of a man sitting on top of a stone bench

The Plutonium, or Hell's Gate, with a statue of Hades and Cerberus, at the Heirapolis. Hierapolis is an exceptional example of a Greco-Roman thermal installation established on an extraordinary natural site, with scattered Greco-Roman ruins including a Temple of Apollo, a necropolis, theatre, and Plutonium. The Plutonium was seen as a gateway to the underworld and a place of communication with the underworld deities because of the toxic gasses that emerge from a hot spring inside the cave