The armillary sphere is an ancient navigation device that guided sailors through the position of the stars in the night sky. Portuguese explorers used armillary spheres for travel around the world and made the country an oversea-Empire. The tool has been a national Portuguese symbol for more than five hundred years. The “Fortress of Cresmina Art Center” is a symbol that fusions art, architecture and landscape. A testimony that merges the historical legacy and the contemporary language. The building is generated from a 70-meter-diameter sphere, sectioned and inscribed in the geometry of the fortress. The result is a curve skin, a simple, pure and powerful gesture that evokes Mediteranean and local architectural references. Thus it creates a sober icon, a new landmark that increases the role of landscape as immovable presence. Through the physical immersion of the museum inside the ruins, which remains intact, spatial tensions, contrasting colors and textures were created, and at the same time a synergistic link that transforms the fortress and the building into a new indivisible unit. Inside the building, each floor takes to the limit the programmatic connections, spatial relations and the interaction with the ancient wall and the landscape, through strategically-chosen magnificent views. The building maximizes the poetics of a full-of-history and nature environment, to convey a simple, silent and inspiring beauty.