Barcelona’s Modernism architects have left the city with a number of fantastical buildings on what is known as the Block of Discord. Even if you do not enter to tour, the buildings are worth the stroller walk-by. Antoni Gaudi’s own Casa Batllo, a former house, is now a museum dedicated to modernism. Outside, the building appears jeweled with color and light playing off of its curves and columns. Gaudi’s special mosaic touch is also on display here, and let the kids decide what the balcony structures look like. Casa Mila, known as La Pedrera, was also designed by Gaudi and built as an apartment building, which it remains today. Visitors can head to the rooftop, where chimneys were turned into sculptures.