CASTELNAUDARY, a town of south-western France, in the department of Aude, 22 m. W.N.W. of Carcassonne, on the railway to Toulouse. Pop. (1931) 6,003. It probably represents the ancient town of Sostomagus, taken during the 5th century by the Visigoths, who, it is conjectured, rebuilt the town, calling it Castrum Novum Arianorum, whence the present name. Early in the 13th century the town was the scene of several struggles during the war against the Albigenses. It is finely situated on rising ground in the midst of a fertile and well-cultivated plain, on the Canal du Midi, which here widens out into an extensive basin lined with warehouses. The church of St. Michel (14th century) has a street running beneath its tower. There is a num ber of flour-mills, as well as manufactories of earthenware and tiles; trade is in lime, timber, grain, fruits, wine, cattle and farm implements.