The Metropolitan Railway Co was a passenger and goods railway that served London from 1863 to 1933. The line connected the main railway stations of Paddington, Euston and King’s Cross with the City of London. Sections of the line had to be constructed beneath the ground and used the ‘cut and cover’ method of constructing tunnels as well as digging tunnels in later sections of the line. The railway line opened in 1863 and consisted of wooden carriages hauled by steam locomotives. It was the world’s first underground railway to carry passengers. The original line was extended, reaching Hammersmith in 1864, Richmond in 1877. The building of the line northwards to Harrow encouraged the development of the new suburb in 1880. Electricity was introduced in 1905 and by 1907 multiple electrically powered units operated across the line. Outlying districts did have to wait to be electrified. The company developed land for housing along the length of the line, resulting in increased passenger numbers. In 1933, the company amalgamated with the Underground Electric Railways Company of London and the city’s tram and bus operators to form the London Passenger Transport Board.