This study examined public building remodeling projects in France. Through investigating cases of ancient buildings remodeled in France, the study aimed to provide fundamental data and analysis for remodeling public buildings. Accordingly, seven cases were analyzed in terms of remodeling methods, architectural characteristics, methods of conservation, and restoration of ancient historical buildings, as well as a change of usage of an existing building. As a result, this study found the criteria of French ancient building remodeling. The remodeling methods of an existing building vary in their goals and strategies depending on how the old architectural elements are persevered, as well as how new elements are added to form their unique characteristics. Thus, the remodeling methods are classified into four types based on causes: restoration, extension, renovation and rebuilding. Such methods are used jointly rather than individually. The ancient building remodeling is the process of recreating new functions and new artistic values to preserve the cultural and artistic values of existing historic buildings.