The procession as a ritual form draws its strength from two historical models or commonplaces: the triumphal entry in ancient Rome and the entry of Christ into Jerusalem. These two archetypal processions are themselves closely intertwined in that Christ's entry took place within the context of the Roman Empire and could be interpreted as an inversion, even a mockery, of the Roman triumph. An occasion at which this complex relationship between the Roman triumph and Christ's entry was acted out to an eminent degree was the Possesso, a procession by which a newly elected Pope took possession of the city of Rome. This article takes a series of visual representations of Possesso processions in the seventeenth century as a point of departure for a discussion of the complex relations between, on the one hand, participants and spectators and, on the other, architectural space and moving bodies. It also explores the ambivalent role played by ancient monuments and ruins in the staging of the Possesso.