The Bakerloo line is a line of the London Underground, coloured brown on the Tube map. It runs partly on the surface and partly at deep level, from Elephant and Castle in Central London, via the West End, to Harrow & Wealdstone in the north-western outer suburbs. The line serves 25 stations, of which 15 are below ground. It was so named because it serves Baker Street and Waterloo. North of Queen’s Park (the section of the line above ground), the line shares tracks with London Overground’s Watford DC Line and runs parallel to the West Coast Main Line.
Opened between 1906 and 1915, many of its stations retain elements of their design to a common standard, the stations below ground using Art Nouveau decorative tiling by Leslie Green and the above-ground stations built in red brick with stone detailing in an Arts & Crafts style. It is the ninth busiest line on the network, carrying over 111 million passengers annually.