The Mystery of the Ancient Roman Tunnel to Hell
There is a place on the northern shore of the Bay of Naples that has long been steeped in history, mystery, myth, and magic. Known as the Phlegræan Fields, it is a desolate place; a barren wasteland strewn with rubble and intersected by deep underground vents that belch out choking fumes and fire. Legends and strange phenomena cling to this hellish, smoke-wreathed landscape, so it is perhaps no wonder that these fields are a location believed since ancient times to hold a tunnel that leads to Hell itself.
The Phlegræan Fields is a plateau that is part of an ancient volcanic caldera not far from Mt. Vesuvius, the volcano known for laying waste to the once great city of Pompeii. The heavily volcanic area, which is pitted with steaming vents, sulphur spewing crevasses, and even flaming holes in the ground, was well-known in Greek and Roman myth and is heavily associated with stories of magic and prophecy.
http://mysteriousuniverse.org/2014/09/the-mystery-of-the-ancient-roman-tunnel-to-hell/