La Peña (The Rock) is one of the areas most deeply affected by both Bilbao’s industrial past and its subsequent post-industrial transformation. For much of the twentieth century, the site functioned as an open-pit mine, encircled by workers’ housing. By the end of the century, it had retained the form of a narrow, curved strip of land caught between the excavation and a steep natural hillside. This condition was further intensified by the insertion of new infrastructures, with the area crossed by two highways and several railway lines.

In this context, the sports complex is conceived as an instrument for the social transformation of the neighborhood in the twenty-first century, and currently stands as its only public facility.

The project had to be developed on an almost impossible site: a residual, reduced, and irregular plot, constrained between a vertical rock face of approximately 120 meters, two highways, three superimposed railway tracks, a metro station, parking accesses, narrow pedestrian paths at the rear, the misaligned façades of adjacent housing, and the metallic structure of a pre-existing fronton. In addition, the perimeter presents a continuously shifting topography, with multiple levels and highly diverse urban conditions.

The building emerges as an irregular volume directly shaped by these constraints. Rather than imposing form, the project results from the accumulation of easements, infrastructures, and spatial tensions that define the site.

The design strategy consists in defining a single constructive system capable of responding to this complexity: a prefabricated reinforced concrete element that adapts to all conditions. The project explores how broader urban reflections—industrial, infrastructural, demographic, and social—can be condensed into a minimal architectural operation.

This system is based on a simple, almost elementary component: a black precast concrete strip. Through limited variations—incorporating glass panels, operable elements, lattices, and different degrees of openness—it is able to resolve all the requirements of the building envelope.

The repetition of this element generates a semi-transparent concrete skin, a unified solution capable of negotiating the building’s multiple relationships with its surroundings. Its variability allows the façade to respond differently depending on orientation, proximity, and programmatic conditions.

Internally, this system defines a continuous social space that overlooks both the stacked sports facilities—arranged vertically due to the limited footprint—and the city beyond. This intermediate space, located between the envelope and the program, operates simultaneously as entrance hall, circulation system, and spatial organizer. It makes the vertical structure of the building legible and, in a region characterized by low natural light, introduces overhead illumination that fills the interior with a dense, almost material light—particularly significant in a former mining environment historically deprived of it.

The porosity of the envelope activates the collective dimension of the building, engaging with the social intensity of the city. The concrete system produces an architecture that is simultaneously open and intimate, allowing users to modulate its degree of transparency. In this sense, the building does not impose a fixed condition; it enables individual decisions about exposure and privacy.

At night, the façade transforms into a pixelated surface. The characteristic blue tone is not produced by artificial lighting or glass treatment, but by the reflection of the swimming pool water onto the interior surfaces. The optical properties of water—its fluidity and translucency—are thus projected outward, communicating with the surrounding urban environment.

This phenomenon establishes a connection between the interior and the city that is not strictly visual but experiential. It allows for a more nuanced and personal relationship between the building, its users, and its context.