From the Wikipedia page [1] Ludgate Circus tube station was planned in the 1970s to be built as part of phase two of the London Underground's Jubilee line near Ludgate Circus. Preliminary preparation work was begun before the plan was postponed due to lack of funds. When the Jubilee line was extended in the late 1990s, it took a different route south of the River Thames and the phase 1 portion of the line from Green Park to Charing Cross was taken out of passenger use.