This paper addresses two questions. First, when and to what extent did capital markets integrate north and south of the Alps? Second, how mobile was capital? Analysing a unique new dataset on pre-modern urban annuities, we find that northern markets were consistently better integrated than Italian markets. Long-term integration was driven by initially peripheral places in the Netherlands and Upper Germany integrating with the rest of the Holy Roman Empire where the distance and volume of inter-urban investments grew primarily in the sixteenth century. The institutions of the Empire contributed to stronger market integration north of the Alps.