The generic city is a theoretical proposition that there is a universal city with many spatial and functional invariants across cultures. According to this theory (based on an extensive study of hundreds of cities and settlements ancient and modern around the world): all cities are comprised of a very small number of long lines and a very large number of short lines, and these constitute a dual system made up of foreground and background networks with different geometries: the foreground network, made up of longer lines and nearly straight connections and the background network, made up of shorter lines with more near right angle connections, and so more localised and with less linear continuity. Functionally, the foreground network takes a more or less universal form of a network of linked centres at different scales, and has emerged to maximise grid-induced movement, driven by micro-economic activity. The background network is largely residential, and is configured to restrain and structure movement in the image of a particular culture, and so tends to be culturally idiosyncratic, often expressed through a different geometry and this makes the city as a whole look spatially different.
Hillier, B. (2007), Space is the Machine: A Configurational Theory of Architecture. Space Syntax: London, UK. pp.vi-vii.
Hillier, B. (2010), The Need for A Spatial Ontology for Societies, the Space Syntax Workshop at the European Archaeological Association Conference. The Hague, Netherlands.