urban centers with more than ten million residents back in one nine hundred fifty the only megacities were new york and tokyo today there are thirty three of them. megacities promise access to well paying jobs modern health care schools and universities. urbanization is stagnating in europe the world s biggest and most densely populated cities are in asia. but the fastest growth in urban populations is forecast for africa. an example of explosive urbanization is lagos in nigeria one of the fastest growing cities in the world. and here the problems of rapid growth are impossible to oversee living space in crowded urban centers become scarce hence expensive worldwide twenty five percent of city dwellers already live in informal settlements or slums. in these