The new *Cultural Centre* in Cartaxo stands out for the bold in situ exposed concrete cantilever that, like a “belly of a whale”, projects itself onto the sidewalk and foyer to house the main auditorium. This public building is located between two gables, taking on the modest urban scale of the main square of Cartaxo. The building introduces an iconographic and public character that balances the relationship between the site exiguity and the extensive programme. The foyer on the ground floor is strongly related to the main civic square of the city, thus emphasising the public character of this building. The cinema is located in the basement, and the main hall was raised from the ground, with the capacity for 332 spectators. Transparency and permeability allow for a visual and spatial porous relationship to be established with the square. From the outside one senses the movement of its users within the building. A flow is generated between the interior of the building and the exterior, which is performed and accentuated by the bulging curvature of the exposed concrete of the “whale’s belly”. Part of the façade is occupied by a mediating element of scale, a concrete and glass screen enabling one to inhabit the periphery and the exterior wall. The public spaces are constructed with exposed concrete, slate floors and timber studs walls, thus emphasizing the presence of the character of these materials. Strong colours, bright yellow and red are used in the back stage areas, revealing to the street a somewhat lively character of these part of the building programme. In the two halls, light is revealed as if it was sculptured out of the walls and ceilings surfaces.