The station is served by the Circle, Hammersmith & City and Metropolitan lines, and is situated between Farringdon and Moorgate stations, in Travelcard Zone 1. Until 2009, Barbican was additionally served by Thameslink services to and from Moorgate.
Barbican station lies in an east-west-aligned cutting with cut-and-cover tunnels at either end. The modern entrance gives access from Aldersgate Street, through a 1990s building, to a much older footbridge leading to the eastern end of the platforms. To the north of the station are the rears of buildings that face onto Charterhouse Street, Charterhouse Square and Carthusian Street. To the south are the rears of buildings that face onto Long Lane, and to the west is Hayne Street. The station is close to the Barbican Estate, Barbican Centre, City of London School for Girls, St Bartholomew-the-Great, and Smithfield.
The station was opened with the name Aldersgate Street on 23 December 1865 on the Moorgate extension from Farringdon. The station's name was shortened to Aldersgate on 1 November 1910 and it was renamed again on 24 October 1924 as Aldersgate & Barbican. On 1 December 1968 the station's name was simplified to Barbican.
Train services were disrupted during the Second World War when the station suffered severe bomb damage in the Blitz, particularly in December 1940. This led to the removal of the upper floors, and in 1955 the remainder of the street-level building was also demolished.
Increasing traffic by other companies, including goods traffic, led to the track between King's Cross and Moorgate being widened to four tracks in 1868; the route was called the 'City Widened Lines'. Suburban services from the Midland Railway ran via Kentish Town and the Great Northern Railway ran via Kings Cross. British Rail services to Moorgate were initially steam operated before being converted to Cravens-built diesel multiple units and British Rail Class 31 locomotives class hauling non-corridor stock which remained in operation until the mid-1970s.