Museo Reina Sofía

Every day, hundreds of people file into Room 206 and stand in silence before a painting that's 7.76 meters wide and 3.49 meters tall, rendered entirely in shades of black, white, and gray. Picasso's Guernica is the most famous anti-war painting ever made, and it spent more time outside Spain than inside it. Picasso painted it in his Paris studio in 1937, responding to the Nazi bombing of a Basque town that killed hundreds of civilians in a three-hour aerial assault. The painting was exhibited at the Paris World's Fair, then spent decades at the Museum of Modern Art in New York because Picasso refused to let it enter Spain while Franco was in power.

The painting finally came home in 1981, six years after Franco's death. It first went to the Prado, then moved to the Reina Sofia in 1992 when the museum opened in a converted 18th-century hospital. The building itself is a fascinating hybrid — the austere stone walls of the original Hospital General, designed in 1566, now punctuated by three glass elevator towers added by British architect Ian Ritchie in 1988. A massive Jean Nouvel expansion in 2005 added a striking red-roofed annex on the south side.

But everything revolves around Guernica. The painting cannot be loaned, cannot travel, and cannot be photographed (though people try constantly). It sits behind a barrier, filling an entire wall, and the screaming horse at its center remains one of the most gut-wrenching images in all of art. Picasso completed the canvas in just over a month, working in a frenzy documented by his partner Dora Maar's photographs.

Beyond Guernica, the Reina Sofia houses Spain's national collection of 20th-century art, including major works by Dali, Miro, and Juan Gris. But let's be honest — most people come for one painting, and that painting delivers.