Calais (France), city in northern France, in Pas-de-Calais Department, on the Strait of Dover, opposite Dover, England. Calais is the eastern terminus of the Channel Tunnel, a 50-km (31-mi) long passageway beneath the English Channel that opened in 1994. The city is also a seaport (notably for ferry traffic with England) and a fishing and manufacturing center; products include lace, embroideries, processed food, lumber, and cables. Points of interest include the Church of Notre Dame; the Tour du Guet (13th century), a watchtower that served as a lighthouse until 1848; and the new city hall.

Because of the importance of its harbor and its position controlling communications between England and France, Calais was often the victim of military conquest. In 997 Baldwin IV, count of Flanders, improved its harbor, and it was fortified in 1224 by the count of Boulogne. In 1347 it was captured by the English after a long siege and held until 1558. From 1596 to 1598 it was in possession of the Spaniards, but was returned to France by the Treaty of Vervins. During World War I (1914-1918); it was the principal debarkation port for British forces. In World War II, Calais was the scene of fierce fighting (1940, 1944) and suffered much damage. Population (2005 estimate) 74,500.