The “Musée Histoire de Paris Carnavalet” is the starting point for visitors of Paris and social scientists to better understand the making of this metropolitan city throughout centuries. The only common factor over the years is the astonishing determination to reinvent the city every 100 years whilst the best features of the previous periods are preserved. It is the concern for the very long-term time horizon that makes the city quite unique. Even a social revolution (1789) unlike most other countries managed to preserve most buildings, churches and royal palaces. Restorations are undertaken with a careful approach to shield its architectural and social heritage. Even the radical transformation by Haussmann over almost 20 years until 1870 to build large corridors in the city is subject to revision in modern visions of the future of Paris. The app of the museum is very helpful to learn more details about each chosen object of the permanent exhibition. The social fabric of the city can be studied further through app’s feature when representatives of local social organizations speak about their personal piece within the huge collection on display. The larger the “fundus”, the more the rationale for selecting pieces becomes an issue. (Image: Musée Histoire de Paris Carnavalet inner court 2025).