The disposition on the ground and the typological layout of the U15 office building articulate and specify the general master plan guidelines in relationship to the specific features of the site and of the overall design of the open spaces. The large dimension of the building plot and of the maximum building envelope given by the master plan is interpreted by folding its perimeter inwards to generate a new layout which unites the advantages of an H-shaped scheme to that of a centralized one. The continuous perimeter “skin” which delimits the interior spaces is divided in several layers which donates depth and a strong light and shadow effect: the inner wall alternates a ribbon window band with an opaque one faced by anodized aluminum panels in natural warm grey, pale gold, light brown shades. The exterior system of brise-soleils in aluminum sheets folded in different profiles, pierced by an array of custom-designed holes and treated with different anodized natural colors protects the windows from the east and west low sun transforming the building in a sort of large tree-trunk with an iridescent bark. The design of the surrounding open spaces alternates paved and green surfaces; the former shape the paths reaching the main atrium from south and east, and offering themselves as a pleasant dehors for the ground floor offices.