This project aims to contribute to the scientific literature on ‘polycentric urban regions’ (PURs). In its most basic guise, the PUR notion applies to regions characterised by the presence of a set of nearby cities that are of roughly equal importance. A well-known example is the Dutch Randstad, where roughly equally-important cities such as Amsterdam, Rotterdam, The Hague, Utrecht, and Delft are regionally clustered. In the scientific literature, PURs are hypothesized to be an increasingly important type of regional formation. However, there is as yet no systematic ‘global map of PURs’ which would help substantiating such claim, while this absence of a global map makes it also difficult to systematically assess all sorts of features that are commonly linked to PURs. This can in turn be traced back to the well-known data complications involved in comparative urban research at the global scale. In this project, we will develop the first-ever global mapping of PURs by applying innovative algorithms to satellite images of population densities. Importantly, this mapping is not an end-goal in and of itself, but rather a crucial step to provide the literature with an easily accessible and state-of-the-art benchmark for situating research efforts. The project in and of itself will also engage in such exercises, while results will be made available to the scientific and non-scientific community alike by means of an interactive and state-of-the-art cartographic website.