Casa O Cuatro organizes its public and private areas through volumes of pure geometry that contrast in both form and materiality. The upper volume, clad in dark stone, appears to float above a light and transparent ground floor that houses the social areas with a strong openness to the exterior. A double-height corridor connects the interior spaces, encouraging the entry of natural light. The indoor-outdoor relationship is reinforced through terraces, sliding doors, and stone materials that create a continuous transition. The garden acts as an articulating axis: on the ground floor, it connects with the social areas through large windows; in the basement, it unfolds to illuminate and link spaces such as the gym and play areas. Wood adds warmth and complements the material palette. Solar orientation guided the design: large windows and roof perforations allow light to enter throughout the day, while strategic overhangs regulate sun exposure, ensuring thermal comfort. Despite the consistent use of materials, each space was endowed with its own identity, achieving a balance between formal unity and spatial diversity.