Malinta Tunnel

The Malinta Tunnel is a tunnel complex built by the United States Army Corps of Engineers on the island of Corregidor in the Philippines. It was initially used as a bomb-proof storage and personnel bunker, but was later equipped as a 1,000-bed hospital. The main tunnel, running east to west, is 831 feet (253 m) long, 24 feet (7.3 m) wide and 18 feet (5.5 m) high.^[2] Branching off from this main shaft are 13 lateral tunnels on the north side and 11 lateral tunnels on the south side. Each lateral averaged 160 feet (49 m) in length and 15 feet (4.6 m) in width.^[1]

• http://en.wikipedia.org/wiki/Malinta Tunnel