It is a sub-surface station served by trains on the Circle and District Lines. The station is located at the junction of Queen Victoria Street and Cannon Street and it is within easy walking distance of Cannon Street tube station.
The station was opened on 3 July 1871 by the Metropolitan District Railway (MDR, now the District Line) when the company extended the line from Blackfriars. The station became the new eastern terminus of the MDR.
The MDR connected to the Metropolitan Railway (MR, later the Metropolitan Line) at South Kensington and, although the two companies were rivals, each company operated its trains over the other’s tracks in a joint service known as the Inner Circle.
From 1 March 1883, the District operated a service between Mansion House and Windsor, using GWR tracks from a junction installed just east of Ealing Broadway, but it was unremunerative and ceased on 30 September 1885.
In 1897 the MDR obtained parliamentary permission to construct a deep-level tube railway running between Gloucester Road and Mansion House beneath the sub-surface line. The new line was to be an express route using electric trains to relieve congestion on the sub-surface tracks. Mansion House was to be the terminus of the express route with platforms 71 feet below the sub-surface platforms.
No immediate work was carried out on the deep-level line, and the subsequent take over of the MDR by the Underground Electric Railways Company of London and the resignalling and electrification of the MDR’s routes between 1903 and 1905 meant that congestion was relieved without needing to construct the deep-level line. The plan was dropped in 1908.
In the 1920s the station entrance was rebuilt to a design by Charles Holden. It featured a tall glazed screen with Underground roundel similar to his station designs for the extension to Morden of the City & South London Railway (now the Northern Line) opened between 1924 and 1926.
In 1949, the Metropolitan Line operated Inner Circle route was given its own identity on the tube map as the Circle Line.