The website of the Grand Paris’s tourist’s office presents the Saint-Ouen flea market as “the only urban site, in France, classified for its atmosphere.” The area classified as "Area of Architecture and Heritage Value" (formerly ZZPAUP) is protected from all destruction and modification that are subject to a regulation since 2001. In this paper we propose to analyze from an ethnographic view of this first classification of an atmosphère as a heritage. After examining the spirit of the place, we will question the perspectives of different stakeholders in this market space and see how they take advantage of this classification.