The urban regeneration policies carried out in Marseille during the last twenty years have had a strong impact on the historic centre and the degraded port districts. The public space has been transformed and became the favoured tool of a renewed image of the city, taking only partially into account the social practices of the inhabitants. The article focuses on the temporary urban experiences introduced by collectives of architects in spaces forgotten by the public authorities and which try to give a concrete response to the inhabitants’ expectations. The article explores the consequent on-going process of updating the participatory urban planning practices.