This paper deals with the challenge in relocalising the Paris MNATP (Museacute;e National des Arts et Traditions Populaires) to Marseille and in crating there a new museum: the Museacute;e des Civilisations de l''Europe et de la Meacute;diterraneacute;e (MCEM). This large transformation gives the opportunity to discuss of the role of a so called "museacute;e de socieacute;teacute;" in French (museum of society) for Europe and Mediterranean. To conceive and lay out this "citizen project" on this huge geographical scale, i.e. an institution able to set in each citizen''s mind of this area that he can be a full actor in the long-term construction of living cultures forming the civilisations of Europe and Mediterranean today : here is the challenge, and therefore, the bet of the forthcoming MCEM. From the reflections led around this huge project, this contribution attempts to enlighten the role kept by such a museum in our societies submitted now to deep overturnings. The Project For the first time in France a national museum will move to the provinces, to Marseille.By decision of the Ministry for the Arts the Museacute;e National des Arts et Traditions populaires (MNATP) will be transformed into a museum of European and Mediterranean civilisations. In association with all the territorial organizations that support it (city of Marseille, regional council of the department of Bouches-du-Rhocirc;ne, region of Provence- Alpes-Cocirc;te d''Azur) and with the participation of the public institution Euromeacute;diterraneacute;e and of the autonomous port of Marseille a major cultural project will be erected at the entrance of the port of Marseille. The project is supported by the European Community. Owing to the richness of its patrimony, the greatest French museum for social issues was obliged to widen its horizon and reinvent itself as the Museacute;e des Civilisations de l''Europe et de la Meacute;diterraneacute;e. A new scientific and cultural project was born, elaborated by the museum team and enriched with the works produced by a scientific committee composed of national and international specialists. In addition to its function of patrimonialization and preservation of folk memory the new institution with its essentially important research laboratory aims at playing a real social role. That is the reason why the future museum will not be centered on its collections but on the public and its questionings, patrimony being considered as a raw material that can be used as a testimony, to introduce counter-arguments, to arouse from the public''s own experience reminiscences, reflexions, or simply new questionings. The museum will be a sort of forum, a space for discussions where displays of reference works and temporary exhibitions will be structured around fundamental social issues. The new museum will be located in the restored Fort Saint-Jean and in a new adjoining building of symbolic architecture erected on pier J4-space Saint-Jean at the entrance of the port of Marseille. The Direction des Museacute;es de France is the contracting authority assisted by the Etablissement public de Maicirc;trise d''Ouvrage des Travaux culturels.