The Fortress of Cresmina is located on a bluff overlooking the Atlantic Ocean, close to the edge between land and sea, due to its unique geographical position it represents symbolically the last bastion of the world built: Actually the architectural building is strongly altered from its original construction and it is possible to appreciate only the exterior walls and its pentagonal plant, so the fortress is a fence from the pentagonal shape whose content is completely lost. The design process has two purposes: the preservation of existing system, and the construction of accessible spaces inside the fence. The volumes are located under the central space to minimize the impact of the new construction, so from the exterior the visitors can see are only the irregular shapes of skylights. In order don't change the Fortress's skyline, the skylights height is lower than the existing walls, and they have double functions: in the daytime they bring light to the underground spaces, while at night-time, being illuminated from within, they will look like shining and brilliant stones protected from the historical fence. As described above, the functions provided by the program are contained in amorphous volumes located in the underground floor and all spaces are connected by an exhibition route, which traces the pentagonal shape of the plant. Access to the underground floor is guaranteed by two ramps, positioned in the central axis, designed like two inclined planes etched in the landscape.