Algiers is the capital and largest city of Algeria. According to the 1998 census, the population of the city proper was 1,519,570 and that of the urban agglomeration was 2,135,630. In 2009, the population was about 3,500,000. An estimate puts the population at about 3,574,000 as of 2010. Algiers is located on the Mediterranean Sea and in the north-central portion of Algeria.Sometimes nicknamed El-Behdja or alternatively Alger la Blanche for the glistening white of its buildings as seen rising up from the sea, 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, 122 metres above the sea. The casbah and the two quays form a triangle.