Henri Salesse. Photographic Investigations, is the presentation of a work that is remarkable in every way, carried out after the Second World War by Henri Salesse, photographer employed by the Ministry of Reconstruction and Urban Planning (MRU). With these two photographic campaigns (Slums, Rouen, 1951, and Sociological Survey for the Musée de l'Homme, Petit-Quevilly, 1952), the photographer gives us a collection of exceptional quality on the working-class neighborhoods of these two cities. These 300 photographs, social testimony and heritage survey at the same time, constitute a document in line with the work of Jacob Riis or Walker Evans. Henri Salesse does not seek to make miserable photographs, but on the contrary to highlight the dignity of the people photographed. In this sense, it is closer to documentary photography, photography at work in a more assertive manner at this time in the United States and Germany, than to humanist photography then very fashionable in France. A singular work in its scale and density, these Photographic Surveys constitute the high point of the daily production of this “technical construction inspector, qualification of photographer”. The unearthing of this photographic collection by Henri Salesse allows us to become aware of the exemplary series of this “grey” photography (administrative or industrial), which remains the submerged part of the history of photography.