Laurel Caverns State Park is Pennsylvania's first and only underground state park, with 426 acres of mountainous terrain on Chestnut Ridge in Fayette County. The calcareous sandstone cavern system is the largest in Pennsylvania and the focal point of the park. Access to the aboveground features and trails is free. Cave tours are offered by the Laurel Caverns Conservancy for a fee. The park adjoins thousands of acres of Forbes State Forest.