A 1,215-foot tunnel transports pedestrians beneath the River Thames.
Opened in 1902, the Greenwich Foot Tunnel cuts 50 feet deep below the surface to take pedestrians under the River Thames from Greenwich to the Isle of Dogs.
The cast iron tunnel is 1,215 feet long and covered with around 200,000 white tiles. It was created as a way for workers who lived in south London to get to work at the docks on the Isle of Dogs, replacing a ferry service, although now it offers 24 hour access to any travelers who need to cross the London river.
During World War II, the northern end of the tunnel was damaged in the London bombing, and there you can see it reinforced with a concrete lining and thick steel. To enter the tunnel, look for the glazed dome buildings for access into the underground passageway.
Clancy's comment: Mm ... I'd hate to be halfway across when it springs a leak.