A seaport and the capital of the district of Vianna do Castello, Portugal; at the mouth of the river Lima, which is here crossed by the iron bridge of the OportoValenca do Minho railway. Pop. (1900) 10,000. Vianna do Castello has manufactures of lace and dairy produce. Its fisheries are important. Salmon and lampreys are exported, both fresh and preserved. The administrative district of Vianna do Castello coincides with the northern part of the ancient province of Entre Minho e Douro. Pop. (1900) 215,267; area, 857 sq. m.