Africa's demographic growth is having a considerable impact on the continent's capital cities. Kigali, for example, is set to double its population by 2050. In one of the most densely populated areas in the world, authorities are trying to organise this growth in terms of urban planning and economics. Rwanda, which holds great ambitions on the continent, has plans to turn Kigali into Africa’s major international hub of business and finance. A report by Simon Wohlfahrt and Bastien Renouil.