The Cultural Centre CaixaForum represents the potential of fighting against difficulty, against (pre-existing) constraints. It is built mainly inside a prevailing concrete skeleton that was meant to be an underground parking area. The project coherently resolves two crucial issues when dealing with existing buildings: accommodating the new uses and making them visible (even being underground). The first issue is approached by placing a set of fairly autonomous volumes inside the given grid, looking for a pacific coexistence: two exhibition rooms, an auditorium and cultural workshops. In addition, an administration area and a café. These new volumes are accommodated to the available space without being dominated by the existing structure. Visibility is provided by an exterior canopy that covers the access systems and receives all visitors’ flows: a public space, a small covered plaza. The canopy has curvilinear cut-outs as main formal characteristic. These are a result of the interaction with near-by existing trees. This gesture comes from the aim of achieving an intense relationship between architecture and nature. This element not only covers and protects the main entry, but it also contains natural light. It captures the sunlight and brings it to the underground hall by a great skylight that filters the light through a porous envelope made of aluminium foam. The sunbeams are transformed then in vibrations over the flooring: light becomes matter. The project conceives the superposition of two worlds: an inner world, excavated, solved with a Cartesian, orthogonal architecture, an architecture made to last forever, to remain. The exterior world is represented by a canopy that responds to the contingences, to the limitations, to the bonds and constrictions: this architecture gives response to the willingness of an era and to contemporary sensitivity. Both worlds are connected by a vertical channel of natural light.