This article explores the relation between imperial hegemony, social heterogeneity, and technological change. The abundance of archaeological and epigraphic evidence makes it possible to both reconstruct a historical geography of urban heterogeneity on the global scale, and to explore its impact at the level of individual regions and cities. This article argues that urban heterogeneity became unequally distributed over the Roman Empire, peaking in the core of the empire in central Italy. Emerging heterogeneity created ideal circumstances for technological innovation, and several key innovations from the Roman period can not only be associated with these extremely heterogeneous micro-regions, but also seem to be facilitated by their very heterogeneity. This perspective adds a new dimension to debates about technological innovation in the Roman Empire.