Constructing the Metropolitan Line, London, c 1860s.(01 of07)
Open Image ModalUNITED KINGDOM - OCTOBER 28: Navvies are shown mixing concrete under the supervision of their foreman, during the building of London\'s Metropolitan Railway. The line\'s engineer, John Fowler (1817-1898) commissioned this series of photographs recording the construction of the line, which was the world\'s first underground railway. On January 10 1863, the Metropolitan Railway operated its first service, which ran from Farringdon Street north to King\'s Cross, and west to Paddington (Bishop\'s Road), utilising trains hauled by steam engines. (credit:SSPL/Getty Images)
Early underground train, c 1935.(02 of07)
Open Image ModalENGLAND - MARCH 10: The first line on the London Underground, the Metropolitan line, opened in 1863, between Paddington Station and the City of London. The network quickly expanded. By the mid-20th century the tube lines were electrified. The building of good rail links between London and surrounding towns meant that people could live further from their place of work because they could travel more easily. (credit:SSPL/Getty Images)
Newly Restored Met Loco No 1 Steam Train Travels Along London Underground(03 of07)
Open Image ModalLONDON, ENGLAND - DECEMBER 16: A newly restored steam engine built in 1898, known as Met Locomotive No. 1, travels through Baker Street Underground station on December 16, 2012 in London, England. The train took part in a practice run for a commemorative journey to celebrate the 150th anniversary of the inaugural public passenger journey on the London Underground, the world\'s first underground railway, on January 9, 1863. Met Locomotive No. 1 will retrace the original London Underground journey on a stretch of the Metropolitan Railway on Sunday, January 13, 2013. (credit:Oli Scarff/Getty Images)
Edgeware Road Station(04 of07)
Open Image ModalA group of people make a trial trip on the world\'s first underground railway on the Metropolitan Railway at the Edgeware Road Station in London. (credit:© Hulton-Deutsch Collection/CORBIS/Corbis via Getty Images)
London Transport Tube Car No 3327, 1927.(05 of07)
Open Image ModalUNITED KINGDOM - JULY 11: This London Underground railway car is an example of 1927 \'standard\' stock, and was built by the Metropolitan Carriage, Wagon and Finance Co Ltd. It was first used on the Piccadilly line in 1929, and was transferred to the Bakerloo Line in 1931 and then to the Central Line in 1939, remaining there until it was taken out of service in 1961. Photographed in the former Land Transport Gallery of the Science Museum in London (1966-1996). (credit:SSPL/Getty Images)
Rotherhithe Underground Station, London, c 1950.(06 of07)
Open Image ModalUNITED KINGDOM - JUNE 01: A Metropolitan Railway K motor car emerges from the Thames Tunnel. From Rotherhithe to Wapping, the Thames Tunnel was the first underwater tunnel and the main acheivement of Sir Marc Isambard Brunel (1769-1849). The tunnel is 460 metres long. Work began on the tunnel in 1825 and it opened as a pedestrian tunnel in 1843. (credit:SSPL/Getty Images)
BRITAIN-POLITICS/(07 of07)
Open Image ModalBritain\'s Prime Minister David Cameron rides a new London underground train with Chancellor of the Exchequer George Osborne looks on during a visit to Bombardier Transportation in Derby, February 12, 2015. (credit:REUTERS/Pool/Joe Giddens)