The urban study for Saint Antoine district in Cap d’Ail has been realized in 2007 for the company “Réseaux Ferrés de France”. The plot was an 19° century railway, in a state of neglect, above the Mediterranean sea, and very close to the Monaco border. The building program will be an hotel and a thalassotherapy complex . Consequently the study presents analysis of heights, densities, typologies and history of construction of this district, and gives arguments to public and private operators to define the plot in urban planning documents being processed. This urban study showed compatibility of the RFF Company project with landscaping directives for protection of Alpes Maritimes ‘coast. Preliminary architectural sketches were essential before ulterior urban development studies.