The book tells the story of Clarté, Le Corbusier’s first apartment building. The steel skeleton building completed in Geneva in 1932 is a precursor of the Unité d’Habitation. In 2007 the external envelope was repaired, followed by a refurbishment of the interior, in which preservation requirements are exemplified. The building log book is illustrated with new and historic drawings and photos, and enriched with the building’s history.