CASTEL-SARRASIN, a town of France, capital of an arrondissement of the same name, in the department of Tarn et Garonne, pleasantly situated on the Songuin, near its influx into the Garonne, 12 miles west of Montauban. The walls which formerly surrounded the town have been converted into promenades. It has manufactures of serges and other woolen stuffs, hats, leather, &c., and some trade in corn grown in the vicinity. Pop. (1851) 6950.