Lagos, Nigerian Upcoming Mega City with 42 Slums

About 6,000 people move to Lagos every day, adding to its already bursting population of 15 million to 18 million people. The U.N. estimates the city will swell to 25 million by 2015. The poor arrive to escape the poverty of rural Nigeria and nearby countries; the wealthier, to escape the violence and kidnappings in the country's oil-rich delta region.

Lagos generates $85 million in revenue a month, according to government officials, and hopes to keep the cash flowing so it will have one of the 20 largest city economies by 2020. More