This image shows the historic natural entrance to Mammoth Cave. Archeological evidence suggests that prehistoric Native Americans utilized the caverns from around 4,000 to 2,000 years ago, but then utilization of the cave ceased. It was rediscovered by a bear hunter in 1798. The cavern experienced a period of saltpeter mining during the War of 1812 era, then early exploitation of the cave for tourism began in 1816. Mammoth Cave was authorized as a national park in 1926. The region around the cave became a World Heritage Site in 1981, then an International Biosphere Reserve in 1990. The park now encompasses 53,000 acres in west central Kentucky.