Castelnau (/ˈkɑːsəlnaʊ/) is a road in Barnes, in the London Borough of Richmond upon Thames, south west London, approximately 5.1 miles (8.2 km) west from Charing Cross on the south side of the River Thames.

[2] Castelnau takes its name from Castelnau-Valence, near Nîmes in France: in 1691, the 10th Baron of Castelnau and St Croix, a Huguenot, fled France for England following persecution, [citation needed] and his son, Charles Boileau, settled in north Barnes and his descendants developed parts of the area.

[citation needed] Castelnau was developed after the opening of Hammersmith Bridge in 1827.

Many of the roads in this estate are named after Deans of St. Paul's who had been Lords of the manor of Barnes between the 14th and 17th centuries: Everdon, Kilmington, Alderbury, Kentwode, Howsman and Stillingfleet.

[5] There are also two churches: From around the time of World War II to 1987, the art dealership Abbott and Holder operated a gallery in the house at 73 Castelnau, which was also the home of the founder, Robert Abbott.