"That's what led to the Attenborough and the Mammoth Graveyard documentary," she said. The site is believed to date back to 220,000 years ago. "The finds that were from the site were truly unique," ...

The surface of Mammoth Cave National Park encompasses about 80 square miles. No one knows how big the underside is. More than 365 miles of the five-level cave system have been mapped, and new ...