Inside the houses, the ordinary person’s living represents a slice of life through which it is possible to know many micro-stories. The first tells us that twentieth-century residential construction was built in response to a real and urgent need to provide housing for many people who had been deprived of it by the catastrophes of war or by their influx from the countryside and decaying centers into the city and its suburbs. From these needs, an essential constructive architectural know-how is born and developed regarding the theme of housing, a recurring element in the modelling of the territory. In recent decades, the value of these works, linked to the quality of construction, the composition of domestic space and innovations in the building sector, has been increasingly debated especially about the negative effects on society and the city. The proposed case study demonstrates how it is possible to change the fate of these places with intervention measures that favor the construction of identity bonds between the inhabitants and the urban context. In particular, the analysis focuses on the musealization of a residential cell: the Appartement témoin by Auguste Perret in Le Havre city centre. It is a laboratory for studying the construction history and the designers’ sensitivity, but also an object in which the community recognises its history and identity. Based on this example, some reflections support adopting this method within Italian heritage. What if regeneration also started from the inside, from the space of the house?