It has become customary among economic historians to distinguish four different sources of economic growth (see, for example, Mokyr, 1990, for an exposition). Although these sources are interconnected in many ways and usually occur simultaneously, they are separable at least in the sense that conceivably we could observe one without the others. The four "horsemen of economic growth" are the gains from trade and specialization (also known as Smithian growth after Parker, 1984), technological change, capital accumulation, and efficiency growth due to changes in the internal allocation of resources.In this paper I examine the role of cities in technological change in the rise of the European economies over the long run. Traditionally, the role of cities has been seen above all as one of promoting Smithian growth. Others, however, have stressed the important role of cities in technological change as well. At first glance, it seems rather obvious that cities should have promoted technological progress. On the demand side, cities provided large markets for better and cheaper products. This demand presumably allowed inventors to cover their fixed costs, focused their efforts toward what consumers wanted, and thus sustained invention. Moreover, by their very nature, cities stimulated transportation technology, as they depended on supplies from the countryside.