Clapham South tube station is a station on London Underground's Northern line between Clapham Common and Balham stations. The station is located at the corner of Balham Hill (A24) and Nightingale Lane. The station is in both Travelcard Zone 2 and Travelcard Zone 3. The station was designed by Charles Holden and was opened on 13 September 1926 as the first station of the Morden extension of the City & South London Railway, which is now part of the Northern line. Other proposed names for the station prior to opening were "Balham North" and "Nightingale Lane".