Ruby Falls at Lookout Mountain / Chattanooga, TennesseeIn 1905, due to geographical limitations, the Southern Railroad Company was forced to construct a tunnel along the face of Lookout Mountain and through some portions of the mountain for one of its lines. This tunnel intersected and sealed off the natural entrance to the Lookout Mountain Cave. In doing this, the Lookout Mountain Cave was completely shut off to the public. http://www.rubyfalls.comshot with canon 60D / Sigma 10-20MM Less