'Gate to Hell' unearthed among Turkey's ancient ruins

Archaeologists say they have pinpointed an ancient – and lethal – cave that was once believed to be the entrance to the underworld. 

Working at the World Heritage Site of Hierapolis in southwestern Turkey, Francesco D'Andria of the Italian University of Salento and his team found a cave featuring Ionic semi columns with inscriptions dedicated to Pluto and Kore, the underworld's deities.

D'Andria and his team also found the remains of a temple, a pool, and multiple steps placed above the cave, which is said to closely fit the ancient writings on the site.

"This is an exceptional discovery as it confirms and clarifies the information we have from the ancient literary and historic sources,” Alister Filippini, a researcher in Roman history at the Universities of Palermo, Italy, and Cologne, Germany, told Discovery News. 

Writing in the first century BC, the Greek geographer Strabo portrayed the cave as follows: "[T]his space is full of a vapour so misty and dense that one can scarcely see the ground.  Now to those who approach the handrail anywhere round the enclosure the air is harmless, since the outside is free from that vapour in calm weather, but any animal that passes inside meets instant death.  At any rate, bulls that are led into it fall and are dragged out dead; and I threw in sparrows and they immediately breathed their last and fell. ” 

Strabo's deadly "vapour" – actually CO2 gas – remains in the cave, said D'Andria, who presented his findings at a recent conference on Italian archaeology in Istanbul.

"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,” he said.

In the ancient world, the gate served as a destination for sacred rites. Small birds were given to pilgrims to test the deadly effects of the cave, while hallucinated priests sacrificed bulls to Pluto. The ceremony included leading the animals into the cave, and dragging them out dead.

According to Filippini, the cave survived until the 6th century AD, when the Christians were believed to have abolished it. A series of earthquakes may have put a complete end to so-called Gate to Hell.

But the fiery underworld, it seems, has more than one entrance. In Turkmenistan, a huge flaming crater in the Karakum Desert is known as the "door to hell."

The fiery pit, which measures some 60 meters wide and 20 meters deep, was created in 1971, when Soviet geologists drilling for oil and natural gas accidentally exposed a huge methane reserve. They decided to burn the gas off, and it has been burning continuously since then.