Urbanization has long been considered the best proxy for wealth in the pre-modern period, due to lack of direct measures. This research note examines the latest data on GDP per capita, carefully derived by economic historians on the basis of extensive micro-historical work, for the most important European cases and then tests how well they are proxied by existing urbanization datasets, by Paul Bairoch and Jan de Vries. It concludes that urbanization is a very unreliable proxy for wealth for the period pre-1500 and only slightly better for the period 1500-1800. Only after 1800 does it correlate well with some cases at least. The retrojection of a modern association into the pre-modern period risks distorting econometric studies; it also reflects by now discarded assumptions about the role of towns in pre-modern growth, ones which survive in the literature on the developing world.