"Any animal that passes inside meets instant death. I threw in sparrows and they immediately breathed their last and fell." ...

Near the Norwegian border somewhere in the depths of the Arctic Circle in Russia lies the deepest hole ever drilled, once called "the entrance to hell." The hole was a man-made creation through ...

Dotted across the globe are some of the most unusual tunnels that you could ever imagine, from one being mysteriously made by giant sloths to another that has been labelled an 'entrance to hell'.