Constantine, city, northeastern Algeria, capital of Constantine Province. It is a center for the manufacture of leather and leather goods and woolen and linen goods. It has considerable trade in these products and in cereal grains with Algiers, Tunis, Annaba, Biskra, and Skikda, the last-named serving as the port of Constantine.The gorge is crossed at the northeast angle of the city by the el-Kantara Bridge, a modern 420-foot (130-metre) structure built on the site of earlier bridges. North and south of the city are, respectively, a suspension bridge and a viaduct.
Caves in the walls of the Rhumel Gorge give evidence of prehistoric settlement. By the 3rd century BC, as Cirta, or Kirtha , the ancient Constantine was one of the most important towns of Numidia and the residence of the kings of the Massyli. The city, built in ad313 by the Roman emperor Constantine the Great on the site of the ancient Numidian city of Cirta, stands on a rocky plateau, more than 640 m (2100 ft) above sea level. It is cut off from the surrounding country on all sides except the west by a deep ravine, through which the Rhumel River flows. A viaduct spans the ravine in the south, and bridges cross it in the north and northeast.
Factory making tractors and diesel engines, industry is chiefly confined to leather goods and woolen fabrics. A considerable trade in agricultural products, especially in grain, is carried out with the Hauts (high) Plateaux and the arid south. Population: 449,602.