Baker Street is a London Underground station at the junction of Baker Street and Marylebone Road in the City of Westminster. It is one of the original stations of the Metropolitan Railway (MR), the world’s first underground railway, which opened on 10 January 1863.

Baker Street is in zone 1, which means it is near the center of London, where it is busy. It is the oldest station on London Underground and the oldest underground station in the world.

Baker Street station is the combination of three separate stations, with several booking offices throughout its operational years. Major changes took place in 1891-93 and 1910–12. The platforms serving the main branch of the Metropolitan line towards Harrow, Uxbridge, and beyond are located within the triangle formed by Marylebone Road, Upper Baker Street, and Allsop Place, following the alignment of Allsop place. This station is the second section which opened on 13 April 1868 by the Metropolitan & St. John’s Wood Railway. This was later absorbed by the Metropolitan Railway, which is usually known to them as Baker Street East station.

The station layout is rather complex. The sub-surface station is connected to the open-air Metropolitan line station. This is a terminus for some Metropolitan line trains, but there is also a connecting curve that joins to the Circle line just beyond the platforms that allows Metropolitan line trains to run to Aldgate in the City of London.

Below this is a deep-level tube station for the Bakerloo and Jubilee lines. These are arranged in a cross-platform interchange, and there are connections between the two lines just to the north of the station. With ten platforms overall, Baker Street has the most London Underground platforms of any station on the network.

According to Wikipedia