Herstal (hĕrˈstäl) [key], Fr. Héristal, commune (1991 pop. 36,451), Liège prov., E Belgium, on the Meuse River, an industrial suburb of Liège. Herstal is the center of Belgium's armaments industry. Other manufactures include motor vehicles, aircraft engines, and electrical equipment. The city was once the residence of the early Carolingian mayors of the palace, including Pepin II, who was born there.