Block of Flats in Marshy Hill Estate, Ajah, Lagos

Lagos is a port and the most populous city in Nigeria. It is the second fastest-growing city in Africa and the seventh in the world. The population of Lagos according to the Lagos State Government, was 17.5 million. These figures are however disputed by the Nigerian Government and judged unreliable by the National Population Commission of Nigeria. The latest reports estimate the population at 21 million, making Lagos the largest city in Africa.

Lagos is a metropolitan area which originated on islands separated by creeks, such as Lagos Island, fringing the southwest mouth of Lagos Lagoon while protected from the Atlantic Ocean by long sand spits such as Bar Beach, which stretch up to 100 kilometres (62 miles) east and west of the mouth. From the beginning, Lagos has expanded on the mainland west of the lagoon and the conurbation, including Ikeja (which is the capital of Lagos) and Agege, now reaches more than 40 kilometres (25 miles) north-west of Lagos Island. Some suburbs include Ikorodu, Epe and Badagry, and more local councils have recently been created, bringing the total number of local governments in Lagos to 57.