Africa also boasts many huge, rapidly growing cities, but it's hard to identify many of these places--like Lagos, Nigeria, Luanda, Angola or Kinshasa, the Democratic Republic of the Congo--as bright prospects.

FORBES: New Geographer

Ki-moon arrived in Libreville, Gabon, late on Wednesday, 30 June, from Kinshasa in the Democratic Republic of the Congo.

UN: Secretary-General

Among the likely new entrants are Lima (Peru) , Kinshasa (Democratic Republic of the Congo) and Tianjin (China).

FORBES: The World's Fastest-Growing Megacities