This article investigates the legacy of ancient Phoenician, Greek and Etruscan colonialism in shaping the economic geography of the Mediterranean region. Utilising historical data on ancient colonies and current data on population density and night light emissions (as a proxy for economic activity), we find that geographical areas colonised by these ancient civilisations have higher population density and economic activity in the present day. We also find that ancient colonialism affected the origin and evolution of the urban system of cities and settlements prevalent in the Mediterranean region.