Following the story of the ancient authors 'such as Cicero and following the path of a thermal spring, the Italian archaeologist Francesco D'Andria has found the legendary 'Gate of Hell' know as the Ploutonion. In ancient times priest sacrificed bulls to Pluto by bringing them in front of the entrance which spews poisonous gases still to this day.
The ancient authors like Cicero(106BC-46BC)and the Greek geographer Strabo(64BC-24BC) mentioned the gate to hell in their writings as being located at the ancient site in Turkey, but nobody from modern times had been able to find the site until now.
“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,”
Source or Strabo writing can be found here: http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Strabo/13D*.html
“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,” D'Andria said.
According to Discovery News, the fumes emanate from a cave below the site, which includes ionic columns with inscriptions to Pluto and Kore, gods of the underworld. Also discovered: the remains of a temple, and a pool and stairs placed above the cave. D'Andria is now working on a digital rendering of the site.