or BOURG-EN-BRESSE, a very ancient town of France (supposed by De Thou to be the Forum Segusianorum of the Romans), capital of the department of Ain, on the Reyssouse, in Lat. 46.12. N, Long. 5.13. E. It belonged at one time to the dukes of Savoy, but was taken Bourgeat by the French in 1536, and in 1600 formally ceded to France by the treaty of Lyons. It was an episcopal town from 1515 to 1536. It possesses a civil court of primary jurisdiction, a communal college, and a public library of 19,000 volumes. Several important grain-markets are held in the town, which is in the midst of an agricultural district. There is also a considerable trade in wines, skins, poultry, horses, and cattle. The chief manufactures are linen, cotton, hosiery, and basket-work. In the neighbourhood is the church of Notre Dame de Brou, built in 1511 by order of Margaret of Austria, aunt of Charles V., and considered one of the finest architectural monuments of that age. Vaugelas the grammarian, and Lalande the astronomer, were born here. Pop. (1851) 9698.