Thibaud’s “La fabrique de la rue en marche” places walking at the centre of urban ambience and street formation. Its iconic idea is that the street is made and unmade through pedestrian movement: walking does not merely occur in the street; it participates in producing its sensory and social condition. The theoretical contribution is to make the step an analytical unit, restoring the anthropological force of walking against the dominance of vehicular speed and network abstraction. Methodologically, the essay proceeds close to the ground, following the passer-by and treating the street as both a mobile field of perception and a dynamic domain of fabrication. Its conceptual operation is ambulatory alteration: urban ambiances are continuously transformed by the reciprocal relation between pedestrian flows and sensory flows. The bridge to the wider field connects urban anthropology, mobility studies, phenomenology, sensory geography and street design, making walking an operative method for understanding urban change.