Tunnels of London
A passenger rides the Mail Rail train ride under Mount Pleasant Sorting Office.
(Jack Taylor / Getty Images)The Cutty Sark is a clipper ship built in 1869 for the Jock Willis shipping line. The ship now sits in Greenwich.
(Mike Kemp / Corbis via Getty Images)Railway workers look at original brickwork in the Thames Tunnel.
(Peter Macdiarmid / Getty Images)A print of the Thames Tunnel in the 19th century.
(Print Collector / Getty Images)