Kentucky's cave

Mammoth Cave National Park is a U.S. National Park in central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world. The official name of the system is the Mammoth-Flint Ridge Cave System for the ridge under which the cave has formed. The park was established as a national park on July 1, 1941. It became a World Heritage Site on October 27, 1981, and an international Biosphere Reserve on September 26, 1990. (from wikipedia) 

Mammoth Cave National Park was established to preserve the cave system, including Mammoth Cave, the scenic river valleys of the Green and Nolin rivers, and a section of south central Kentucky. Beneath the sandstone-capped ridges of Mammoth Cave National Park lies the most extensive cave system on earth, with over 350 miles of passageway mapped and surveyed. And yet after 4,000 years of intermittent exploration, the full extent of this water-formed labyrinth remains a mystery. (from here)

The Mammoth Cave is the largest cave in the world. There are a lot of caves in Kentucky. The Natives American used caves as their shelters. Sometimes soldiers in their civil war were also used caves as bunkers and storage places. 

In Kentucky a lot of people go to explore caves in hopes to finding artifacts.