All cities are vulnerable. They have economically, socially, institutionally vulnerable urban space.

In developing countries, vulnerable urban space can be observed typically as substandard informal settlements such as slums or areas occupied by squatters. At present, slum dwellers comprise one-third of the world's urban population of 3 billion, and it has been estimated that the number of slum dwellers will double in the next 30 years if no effective action is taken. Improvement of vulnerable urban areas, which is one of the targets of Millennium Development Goals, is thus an...