This 720-square-foot apartment in Barcelona was renovated and opened up by Nook Architects. Key to the design are the original barrel-vaulted ceilings, which are mimicked in the mixed-use gallery in the front. What was once a central hallway dividing multiple rooms—typical of older apartments—became a new common space that flows into the gallery. Materials were also limited exclusively to those already present in the space—namely, wood, ceramic, and marble. A canopy of original terra-cotta tiles line the barrel-vaulted ceilings, and a minimal aesthetic ties it all together.