The Door to Hell is a natural gas field in Derweze (also spelled Darvaza, meaning "gate"), Ahal Province, Turkmenistan. The Door to Hell is noted for its natural gas fire which has been burning continuously since it was lit by Soviet petrochemical scientists in 1971, fed by the rich natural gas deposits in the area. The pungent smell of burning sulfur pervades the area for some distance.
From Wikipedia: http://en.wikipedia.org/wiki/Door_to_Hell
