Using detailed information on rents of houses in Alkmaar we were able to demonstrate that in the preindustrial epoch, neighbourhoods and even blocks of houses were socially mixed. This was, however, not the case for blocksides: in Alkmaar a string of costly residences ran along the east-west axis of the city. Contrary to what is often supposed this residential pattern did not result from the social structure of early modern society or the lack of intra-urban transport, but from a 'modern' force: accessibility and the value of urban land. We therefore question the widely held view that modernization and industrialization caused a fundamental change in the social structure of cities (and societies). Finally we expanded the scope of our research by including empirical evidence on Amsterdam and drawing the broad contours of a descriptive model for the study of urban growth and residential segregation.