town, Pas-de-Calais département, Nord-Pas-de-Calais région, northern France, near the source of the Deûle River, southwest of Lille. Mentioned as Laid-win (Laivin) in 1104, it developed as a coal-mining centre of the Lens area. Many of the former miners' houses have been restored, and lighter industries have been attracted to the town. Liévin is architecturally modern, its older buildings having been largely destroyed in World War I. Vimy Ridge, site of heavy fighting in World War I, is just to the south. Pop. (1999) 33,427; (2005 est.) 32,200.