M42 beneath Grand Central

[pokerfan]

This is fucking awesome! 'Cities of the Underworld' on the History Channel.

A "secret" sub-basement known as M42 lies under the Terminal, containing the AC to DC converters used to supply DC traction current to the Terminal. The exact location of M42 remains a closely guarded secret and cannot be found on maps though it has been shown on television, most notably, the History Channel program, Cities of the Underworld and also a National Geographic special. The original rotary converters were not removed in the late 20th century when solid state ones took over their job, and they remain for the purpose of historical record. During World War II, this was one of the most guarded facilities as if it were sabotaged, troop movement on the Eastern Seaboard would have been halted.<4> Despite it being a secret, Adolf Hitler was aware of this facility and sent two spies to sabotage it. The spies were arrested by the FBI before they could strike. It is said that any unauthorized person entering the facility during the war risked being shot on sight. This was due to the fact that a simple bucket of sand could easily cripple the rotary converters used at the time. (wiki)