There's a story here. Ruby Falls is inside Lookout Mountain, and at the base of the mountain there's a big cave by the Tennessee River. Right now, it's beside the railroad tracks that run between I-24 and the mountain. The original plan was to build a shaft from up on the mountain to that lower cave so they could open it for tourism. They started drilling the shaft and barely nicked the cave where Ruby Falls is. I think the hole was about a foot in diameter. But air pressure differences made air blow out of it so they realized it was a sizable cave system. After exploring that cave and finding the waterfall they realized that was going to be the cave to tour. I think the elevator actually goes all the way to the other cave.