Boxwork. That's what makes this National Park unique. I've done a lot of cave tours across the country from Virginia and Tennessee to New Mexico and Oregon (and more). I've never seen boxwork outside of this site and this had the most extensive boxwork in the world. What is it already? It's a honeycomb looking structure on the ceiling formed by crystal formations in cracks of limestone. The Park is located in Hot Springs, South Dakota, about an hour south of Rapid City.
