Africa which is more or less as a whole part of the developing world, is home to seven rapidly growing megacities:
Cairo (Egypt), Accra (Ghana), Johannesburg-Pretoria (South Africa), Khartum (Sudan), Kinshasa-Brazzaville (Democratic Republic of the Congo and Republic of the Congo), Lagos (Nigeria) and Nairobi (Kenya).
Just one example for the rapid growth of these cities: Lagos has grown from 300,000 in 1950 to an estimated 15 million by 2007, and the Nigerian government estimates that city will have expanded to 25 million residents by 2015.
In South-Africa, the Greater Pretoria Metropolitan Council took advantage of a movement of renaming numerous places in South Africa by using indigineous African terms. It put forward a new African name for the larger urban area around the cities of Pretoria and Johannesburg: Tshwane, means "we are the same", and has been used in the area since before the Afrikaaner leader Andries Pretorius named today's Pretoria after himself in the 19th century.
Resource: Wikipedia, BBC