Diverse driving forces, processes and actors are responsible for different trends in the development of megacities and large urban areas. Under the dynamics of global change, megacities are themselves changing: On the one hand they are prone to increasing socio-economic vulnerability due to pronounced poverty, socio-spatial and political fragmentation, sometimes with extreme forms of segregation, disparities and conflicts. On the other hand megacities offer positive potential for global transformation, e.g. minimisation of space consumption, highly effective use of resources, efficient...