MNAC

The building is absurdly grand — a palace built for a temporary fair. The Palau Nacional was constructed for the 1929 International Exposition, designed by architects Eugenio Cendoya and Enric Cata in the Beaux-Arts style, with towers, domes, and cascading fountains that make it look like the seat of a small empire rather than an exhibition hall. After the fair ended, the city had to figure out what to do with it. The answer: fill it with the best collection of Romanesque art in the world.

The Museu d'Art de Catalunya officially opened on November 11, 1934, and its Romanesque collection is genuinely unmatched anywhere. In the early twentieth century, teams of conservators physically removed medieval frescoes from crumbling rural churches in the Catalan Pyrenees and reinstalled them in the museum — entire curved apse walls were transferred, creating walk-in chapels that surround you with thousand-year-old painted saints. If they hadn't been rescued, many would have been sold to American collectors or lost to decay.

The fully consolidated museum didn't take its current form until December 16, 2004, when the Romanesque and Gothic collections were finally united with nineteenth- and twentieth-century Catalan art. The range is staggering: from eleventh-century murals to works by El Greco, Velazquez, Ramon Casas, Gaudi's furniture, and Dali.

Stand on the terrace in front of the Palau Nacional at dusk and you get one of Barcelona's great free shows: the Magic Fountain of Montjuic performs a choreographed water, light, and music display against the backdrop of the city below. The fountain was designed by Carles Buigas for the 1929 Exposition and has been delighting crowds ever since.