Metropolitan Railway

From the Wikipedia page

In 1863 the Metropolitan Railway (also known as the Met) opened the world's first underground railway in London. From Paddington the line was built using the "cut-and-cover" method beneath the New Road, connecting the mainline railway termini at Paddington, Euston and King's Cross, and then followed Farringdon Road in tunnel and cuttings to a station at Farringdon Street in Smithfield, near the capital's financial heart in the City. The service was initially provided by gas-lit wooden carriages hauled by steam locomotives.

The railway was soon extended from both ends and northwards via a branch from Baker Street. It reached Hammersmith in 1868, Richmond in 1877 and completed the Inner Circle in 1884, but the most important route became the line north into the Middlesex countryside where it stimulated the development of new suburbs. Harrow was reached in 1880, and the line eventually extended as far as Verney Junction in Buckinghamshire, over 50 miles (80 kilometres) from Baker Street and the centre of London.

Electric traction was introduced in 1905 and by 1907 electric multiple units operated most of the services, though electrification of outlying sections did not occur until decades later. Unlike other railway companies in the London area the Met developed land for housing and after World War I promoted housing estates near the railway with the "Metro-land" brand. On 1 July 1933, the Metropolitan Railway was amalgamated with the underground railways of the Underground Electric Railways Company of London and the capital's tramway and bus operators to form the London Passenger Transport Board.

Today, former Metropolitan Railway tracks and stations are used by the London Underground's Metropolitan Line, Circle Line, District Line, Hammersmith & City Line, Piccadilly Line and Jubilee Line.