City Thameslink is a railway station in the City of London, England. The platforms are underground with a southern entrance on Ludgate Hill just off Ludgate Circus, and a northern entrance on Holborn Viaduct. It is in Zone 1 on the Thameslink route between Blackfriars and Farringdon. Although a through station, for ticketing purposes it is considered a central London railway terminus for journeys to and from the south. City Thameslink is not open on Sundays.
Before its 1990 opening its site was intended for Ludgate Circus station on the cancelled Fleet Line Extension of the (now) Jubilee Line. The station opened on 29 May 1990 as St Paul's Thameslink. The name was changed in 1991, to avoid confusion with St. Paul's London Underground station (Central Line), which is several hundred yards away on the other side of St Paul's Cathedral.