Well, an underground mine definitely has a lot of dirt. And by a lot, we mean 5 miles of dirt trails, ramps and obstacles in a 320,000 square feet of space. Oh, and did we mention it's 100 feet underground?
Check out this abandoned limestone mine in Louisville, Kentucky, that got converted into the world's only underground mountain bike park: the Mega-Cavern Bike Park.
WebUrbanist has the story.
Video clip below.