ABSTRACT
The city can be defined in a general and schematic way as the meeting of density and diversity (Levy, 1999). By density we mean both the extent to which a city is built up and its human density; when we speak of diversity we mean its substance (i.e. the ensemble of its services, its permanent and temporary populations (those who work in the city but do not live there for instance), the morphology of the built environment, public spaces, technical and local networks. This definition -both minimalist and consensual-will serve as the jumping-off point for this chapter. Therefore a city's unique diversity and density is the result of the layout of its morphologies, services and lifestyles - three of the ingredients we cited earlier as central to the changes in urban dynamics today.
