Algiers is the capital and largest city of Algeria, and the second largest city in the Maghreb, with a population of 3,354,000 within the city metropolitan area. Algiers is situated on the west side of a bay of the Mediterranean Sea. The modern part of the city is built on the level ground by the seashore; the old part, the ancient city of the deys, climbs the steep hill behind the modern town and is crowned by the casbah or citadel, 400 feet above the sea.