National Geographic takes you on a tour of the three major levels of activity under New York City. On the first level you’ll see all the power wires, cables, water and gas pipes, and even pipes that have been forgotten about. Go down 30 to 200 feet and find the subway and the major sewage lines. If you dare, travel down to level 3 that goes to 800 feet below the surface. There is lots to explore virtually even if you can’t get the Big Apple this summer.
courtesy of Knovation
