the.com/tunnels
proof that humans, faced with a mountain, would rather dig than walk around
longestSwitzerland's Gotthard runs 57 kilometers under the Alps
escape artprisoners have tunneled out with spoons and patience
oldestBabylon had a river tunnel around 2000 BC
hidden citiesCappadocia's underground network sheltered thousands underground
vision quirknear-death tunnel imagery may stem from oxygen-starved retinas