 Penn's Cave, located just east of Centre Hall, is an all water limestone cave and wildlife center unique in the United States.For centuries the few dry rooms above the water were used as shelter by Native Americans and European trappers; in 1885 the cave was officially opened as a show cavern and the nearby Penn's Cave Hotel was opened the same year.On its 91st anniversary in 1976 both the cave and hotel were placed on the National Register of Historic Places.