Bakerloo Line

The Bakerloo Line is a line of the London Underground System,it is colored brown on the Tube map. It runs partly on the surface and partly at deep level, from Elephant and Castle to Wealdstone.
Deep Level:
These sections are typically much deeper than the sub-surface sections. The deepest point on the whole tube network is 220 feet deep.
History
Originally called the Baker Street & Waterloo Railway, the line was constructed by the Underground Electric Railways Company of London Limited and opened between Baker Street and Lambeth North (then called Kennington Road) on March 10, 1906. It was extended to Elephant & Castle five months later, on August 5. The contraction of the name to "Bakerloo" rapidly caught on, and the official name was changed to match in July 1906.
The Bakerloo Line serves 25 stations and is 23.2km long. It makes 104,000,000 journeys per annum.