Starting from an open and dynamic conception of place as a socio-spatial and temporal assemblage, this paper explores high density urban areas as dynamic environments of social interaction. While Lefebvre's call for a rhythmanalysis of the city, significantly influenced contemporary urban discourse, such understanding still lacks empirical depth. This paper seeks to advance the empirical grounding of rhythmanalysis through a comparative study of nine selected street intersections in London, New York and Melbourne. It explores the links between the observed, filmed and measured daily and weekly rhythms of pedestrian flows on the one hand and density, permeability, grain size and functional mix, the four preconditions of urban vitality according to Jacobs, on the other hand. Further, mapping is used as a means of revealing the forces underlying each place. It is shown that the overlay of regular patterns of everyday habits and routines, rhythms of social interactions and mechanical micro-rhythms of transportation systems, all mediated by urban form, lead to place specific polyrhythms. Place is thus conceived as emerging from the intersection of rhythmic flows, mediated by urban morphology and functional mix.