Algeciras, a seaport and town of Spain, in Andalusia, province of Cadiz, on the W. side of Gibraltar bay, opposite and 6 m. W. of Gibraltar; pop. 18,000. Charles III. rebuilt it in 1760, as a point of annoyance against Gibraltar. It is constructed of stone, and presents a fair appearance compared with many of the smaller. Spanish towns. The port is guarded by a battery called the Fuerte de Santiago. The town is supplied with water conveyed by an aqueduct over the Miel. The principal trade is the export of coal from the neighboring mountains, charcoal, and leather. Two considerable sea fights took place off Algeciras in July, 1801, between the English and French squadrons, and in the second the English were victorious.