Launched by the city of Marseilles, the project Quartiers Libres unites the destinies of the future Saint-Charles’ station and the Saint-Charles – Belle de Mai districts. Due in 2030, the coming of a new underground railway station fosters a global requalification of these areas pushed aside from the city centre by rail infrastructures. Carrying a crossed-reflexion between the strategic scales of the districts (140 hectares) and the operational scale of the to-be-repurposed Saint Charles barracks (7 hectares), the proposed project takes its roots in the Scenarisation method, a process which considers the temporal and spatial breadth of a territory to operate a step-by-step transformation of the ensemble. The Saint-Charles station’s transformation is the occasion to trigger the reinsertion of these districts into the core of the city. Today, the station turns it back to Saint-Charles – Belle de Mai, for the benefit of an exclusive openness on the city centre. A work on the accessibilities and crossings therefore allows a reconnection of the neighbouring districts. Important landmarks for the integration of newly arrived populations, the Saint-Charles – Belle de Mai districts must reinforce this vocation through a wider openness to the city. The topography of the site provides it with a privileged position. It allows future facilities to open themselves up to the Marseilles metropolis. At the core of this urban apparatus, the barrack’s site constitutes the focal point of these issues. The emblematic Muy barrack will host the facilities needed for this reconversion: school, cultural and sporting facilities, shops, activities, accommodations and a forest. All will contribute to intertwine the local and metropolitan vocations of the Quartiers Libres.