A station on the Northern Line in Travelcard Zone 2. The station is served by the Northern line and is at the junction of the Charing Cross and Bank branches to the north and the Morden and Battersea Power Stationbranches to the south. which is the southern junction for the two branches of the line, and is the terminus for many of the trains on the Charing Cross branch. Opened on 18 December 1890.
The Wikipedia page is [1] and the TfL page [2]. Some more information here