The downsides of density, including traffic congestion, contagious disease and crime, were common in Victorian London and classical Rome, just as they are today in Sao Paulo and Lagos. Our urban past provides lessons for developing world cities today. The first lesson, that I highlight, is that...

Africa is projected to have the fastest urban growth rate in the world: by 2050, Africa’s cities will be home to an additional 950 million people. Much of this growth is taking place in small and medium-sized towns. Africa’s urban transition offers great opportunities but it also poses...