Historic District - Historic Cave Entrance and Stairs
This historic site is 200 yards (182 m) north of visitor center, accessible by a footpath.
The natural opening to the cave is considered a sacred place to the Native Americans of the area. It was first noticed by Tom and Jesse Bingham in 1881. Due to its small size, the area surrounding the entrance was enlarged slightly. The limestone surrounding the natural opening appears angular and unweathered, indicating an attempt at blasting. A larger artificial opening was blasted from the surface to natural cave passageway about 30 feet (9 m) SW of the natural entrance between 1884 and 1891. This new entrance was in the form of steeply downward tilting tube. A yet newer entrance was constructed in 1936 by the Civilian Conservation Corps. The floor of the steep early entrance was blasted to produce a gentler grade which connected with the existing wooden stairs. Concrete stairs were poured in this new section and all wooden stairs were replaced with concrete.
The entrance portal was inlaid with large stones creating rock-lined tunnel from the outside to its juncture with natural rock of cave. Inside the entrance portal, a thick-slabbed wooden door with a circular vent was installed. An iron gate was installed inside of the door. The door restricted some of the artificial airflow. Above the entrance portal, a slope of earth fill was added and built up to the level of the parking lot access road. The entrance portal and overlying fill gave the illusion of a natural setting.
The 1936 entrance remained virtually unchanged for over 50 years. A revolving door was installed at the entrance in 1991 to slow artificial air exchange. Park management was concerned about changes to natural cave environment brought about by artificial air circulation. The historic flavor of 1936 entrance remains, but hidden behind the revolving door.