Lille, in northern France, was once an industrial powerhouse. In response to collapsing industry a post-urban tertiary economy was developed under state leadership that bypassed the form and structure of the existing métropole. This has left the city with a parallel métropole that does not engage with post-industrial districts and therefore continuing stigmatisation and disenfranchisement within these neighbourhoods. The dissertation investigates how the post-urban and the post-industrial can be reconciled through socially-motivated economic development in post-industrial blocks. Strategic and opportunistic use of the post-industrial block is shown to have the potential to create a different, urban kind of economic space in which various, specific stakeholders and constituencies can coexist and benefit from one other. This addresses both the post-industrial and post-urban conditions through intensification, rehabilitation, renovation, extension and transformation. It is a strategy that creates precisely the kind of mixed-use, mixed-user, mixed-typology urban form that features prominently in discussions on best urban practice and a different idea of the potential of post-industrial cities. A demolished factory is shown to be more than vacant land, it is the possibility to produce the kinds of urban and social constellations cities are attempting to make today.