As we navigate the maze-like passages, we stumble upon a hidden cave deep within the mine, leading us into an incredible underground world. With ropes guiding the way, we descend into crystal ...

Deep inside a labyrinthine cave in southwestern France, ancient humans who lived around 30,000 years ago carved horses, mammoths and rhinoceros into the walls, a fabulous prehistoric menagerie ...

There are more than 400 abandoned mines across New Jersey. At one point, they were essential to the state economy.