“Time is a construction material,” says 64-year-old architect Emilio Tuñón Álvarez as we stand at the threshold to Madrid’s new Galería de las Coleccionnes Reales (Royal Collections Gallery, or GCR). And he should know: almost a quarter century after his then firm, the globally renowned Mansilla + Tuñón, entered the first competition to design the institution, the $165 million building finally opened to the public this June. A lot has happened since, including the 2012 heart attack that struck down his former partner, Luis Moreno García Mansilla, at the age of just 53. “His death was a disaster, but what could we do?” asks Tuñón, now principal at Tuñon y Albornoz Arqui­tectos, alongside Car­­los Martínez de Albornoz. “We carried on. This is Luis’s final building.”

From below, the Royal Collections Gallery reads as a complex stack of floors of varying heights. Photo © Luis Asín, click to enlarge.