Miro's work is everywhere. Well, that's what Miro did for a living. The cathedral La Sagrada Familia is the best known piece of architecture here. Built by Mr. Gaudi himself, it is by far the gaudiest and craziest looking building in the world. You can climb straight up the towers, but beware, your knees will start to buckle after the 17 trillionth step.
Transportation is fairly easy.
Although everyone can, Catalan is the preferred language.