The historical monuments of Paris have been a heritage shaped since immemorial times by craftsmen who have gathered to create a guild called "Compagnons du Devoir". From the Middle Age to the 19th century, they were everywhere in the architecture and construction of the capital. For example, few people know that the Eiffel Tower was built by the Companions. In the Marais, their work is everywhere. Being a "Compagnon du Devoir " means to be like any other craftsman except for a few differences: one has to live in community for a while and create a masterpiece. It is an unique approach to excellence.