Plans for a Royal Collections Gallery in Madrid began in the 1930s, but the Spanish Civil War put a stop to that. In 1998, the Spanish Government picked up the project again, only to face another hurdle: in 2006, the discovery of a ninth-century city wall dating back to the Islamic era caused another delay. Twenty-five years in the making, the building is finally complete, designed by Luis M. Mansilla and Emilio Tuñón and costing $185 million. It is perched on a hill above the Royal Palace and contains 650 works spanning five centuries. Among its treasures are paintings by the titans Diego Velázquez, Caravaggio, and Francisco Goya. Don’t miss the first edition of the Ceravantes classic Don Quixote. —Elena Clavarino