To this day restorers pay less attention to a building's wall coating than to its other constituent parts. The importance of coatings should not be overlooked for they can reveal a wealth of data on the original construction including information about the building techniques of a region, of a period or of a particular artist. Obsolete since the 18th century -- in the last century bare stone was preferred while cement has been widely used in the present century -- coatings were used for centuries to protect and to decorate building materials. The fact that coatings are often eliminated in the course of repair and restoration work indicates that we are still unable to fully appreciate their contribution toward a better understanding of the building's history and proper restoration. The work undertaken in the courtyard of the Hotel Milsand in Dijon (France) revealed the extent to which the attentive examination of the coating can be useful to the overall archaeological study of a work of architecture. Thanks to the coating, restorers were able to identify the 16th-century modifications which included the addition of a trompe l'oeil decoration to the west wall of the courtyard. Thus, the preliminary archaeological investigation, on which restoration work is based, gives rise to some fundamental questions about restoring. How should the coating be restored? Should it be reproduced? If so, how and in which instances? These questions should be examined in the larger context of the restoration of the entire building. It is necessary that a greater number of studies similar to the one presented here be undertaken for they will undoubtedly add to our knowledge of the history of coatings and will foster a sounder approach to restoration.