The Carthage Underground, near Carthage, MO, is a vast, chilly expanse of marble quarries mostly owned by Americold and used for food production and storage. More than 43 million square feet of warehouse and tunnel spaces join up with other abandoned quarry caves, some complete with underground lakes hosting entire ecosystems. Because of the aggregate, disjointed nature of these spaces, urban explorers often brave the dangers to gain entry from other, connected systems. Some of these intrepid explorers have returned with fantastic tales ranging from the discovery of hidden military installations to witnessing creatures straight out of a horror movie. Check out the links below and be sure to read the comments for more about these strange spaces.