Le Corbusier’s apartment-studio is an iconic object of the twentieth century, combining the indisputable material values of the building with the intangible “sense of place” of an architect’s home. Le Corbusier, who lived there from 1934 until his death in 1965, treated it as a permanent construction site—a unique place of spatial, plastic and constructional experimentation. Phases of change at “24NC” are overlaid as a palimpsest, and the apartment’s “many lives” create major philosophical problems for conservation. A study of its material history over time reveals a simple fact: the “stratigraphy” itself, hard to unscramble yet rich in meaning, is key to the object’s importance. This first monograph on the apartment-studio, richly illustrated with largely unpublished visual material, presents research undertaken by the authors for the Fondation Le Corbusier during preparatory investigations for the program of restoration.