Saint-Omer (săNtômĕr`), city (1990 pop. 15,304), Pas-de-Calais dept., N France, in Flanders, on the Aa River. The chief manufactures are metals, textiles, paper, and beer. The city grew around a monastery founded in the 7th cent. by St. Omer, the bishop of Thérouanne. In medieval times the abbey of Saint-Bertin was famous. Points of interest include the church (now basilica) of Notre Dame (13th–15th cent.), which contains the tomb of St. Omer; the Sandelin Museum; and the ruins of the abbey.