Interesting fact:

This ancient underground complex has seen all sorts of unfortunates stumble in and become lost to the surface world above, from saber-toothed tigers to Native American wanderers and a smattering of cowboys and miners! Specters of these unfortunate souls are now said to stalk this underworld, although the mysterious moaning sounds that lured these travelers in the first place has been impacted by the expansion of the entrance. So you’ll just have to moan about the admissions fee!