If you take the Historic tour while visiting Mammoth Cave National Park, you are going to get just that. This is not the most beautiful part of the park. Though parts are pretty, this tour is about how the cave has been used throughout history. The first big room you enter is the Rotunda, it is here that you see a Revolutionary War era Saltpeter mining operation. Saltpeter is used in the making of gunpowder and was in pretty high demand as you might imagine. 

This photo shows the remains of the operation that was just abandoned and left in place when earthquakes and the falling price of saltpeter halted operations.