Barcelona is an open-air museum of Gaudí masterpieces - mansions, parks, cathedrals, street lamps. Seven of his works in or near the city make up a UNESCO World Heritage Site serial property testifying to the free rein he gave to the design of buildings, gardens and sculptures. The seven are: Parc Güell, Palau Güell, Casa Milà-La Pedrera, Casa Vicens, the Nativity Façade and Crypt of the Sagrada Família, Casa Batlló, and the Crypt of the Colònia Güell. Starting off with a guided tour is a good way of getting the lay of the land and some expert backgrounding on the Modernisme movement before going back on your own.