Mysteries of the Abandoned

Arctic Hell Pit (2x3)

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Traces of a Russian hole to hell in the Arctic, a military base in America's wild west, and a strange looming tower are mysterious deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned. Stories: 1) Salton Sea Test Range, California, USA; 2) Kola Superdeep Borehole, Pechengsky, Russia; 3) Canfranc Railway Station, Aragon Valley, Spain; 4) Power Station IM, Charleroi, Belgium.