The Grand Saint Barthelemy housing estate (Zone Urbaine Prioritaire 1) in Marseilles, built in 1960, has housed many migrants in its subsidised accommodation. Initially neglected and badly maintained, it became an essential reference point for developing urban policy, as militant local associations took root. Links between political interventionism, militant commitment and working class culture, at once fruitful and adversarial, were used in various initatives to help conserve local memories. In its turn, this helped to forge local identities rooted in the post-war estates. The article refers to this internal/external dynamic in its attempt to analyse how such memories are catalysed.