Before Europeans came to North America, Native Americans occupied the continent. But Native Americans themselves report that others lived there before them. Did these humanlike creatures emerge from under ground, from the center of a hollow Earth? Are they still living below us in secret, glimpsed every so often as Sasquatch or Bigfoot, or mistakenly thought to be alien life-forms from UFOs? The possibilities are endlessly intriguing, and until there's an actual probe to the center of the Earth, we have only conjecture and hypothesis to go on. Download and start listening now!