The Third Tunnel of Aggression, built by North Koreans , discovered in 1978 and apparently designed to launch a surprise attack on Seoul. It's 1.7km, 2m high, 2m wide and 73m below ground. We rode the monorail, walked along the tunnel and it's sad to imagine the number of North Koreans died making this tunnel due to lack of oxygen. (www.koreatour.webs.com)
