Edward Soja uses the term fractal city to describe the "metropolarities" and the restructured social mosaic of today's urban landscape or "postmetropolis". In his book, Postmetropolis: Critical Studies of Cities and Regions, he discusses how the contemporary American city has become far more complex than the familiar upper class vs. middle class or black vs. white models of society. It has become a fractal city of intensified inequalities and social polarization. The term "fractal" gives it the idea of having a fractured social geometry. This is a patterning of metropolarities, or an intensification of socio-economic inequalities, some of which Soja tries to pinpoint and discuss.