Archaeologists reportedly have uncovered the cave believed to be Pluto's Gate, the mythological portal to hell, in the ancient city of Hierapolis in southern Turkey.
The site was located among ruins in the area, Italian archaeologists said, according to a report on Discovery.com.
Hierapolis is now known as Pamukkale.
Pluto's Gate was celebrated as the portal to the underworld in Greco-Roman mythology. Pluto was the Greek god of the underworld.
The find was made by a team that was led by Francesco D'Andria, a professor of classic archaeology at the University of Salento.
Pamukkale was already considered culturally significant. It's on the United Nations' list of World Heritage Sites, alongside the pyramids of Egypt, Australia's Great Barrier Reef, East Africa's Serengeti and the Galápagos Islands in Ecuador, among other international sites identified for preservation and protection.
Ancient Hierapolis was a cosmopolitan city where Anatolians, Graeco-Macedonians, Romans and Jews intermingled, according to UNESCO. The city was located on hot springs that were used for thermal spas and baths.
Ancient scholars wrote about Pluto's Gate, claiming that the portal was full of vapor and mist and that any animal that tried to enter would perish.
Strabo, an ancient Greek geographer, wrote that he "threw in sparrows and they immediately breathed their last and fell," Discovery also reported.
The archaeologists apparently witnessed something of this firsthand.
"We could see the cave's lethal properties during the excavation," D'Andria of the University of Salento said, according to the Discovery report. "Several birds died as they tried to get close to the warm opening, instantly killed by the carbon dioxide fumes."