Visionary Catalan architect Antoni Gaudi’s (1852-1926) modernist buildings, seven of which are UNESCO World Heritage sites, dot the city of Barcelona. Visitors cans see them all by following the Gaudi Trail, a self guided walking route. The walk typically begins at the Güell Palace (Carrer Nou de la Rambla, 3-5; 34-9/3472-5775; palauguell.cat), a mansion built for an industrial tycoon in El Raval, then up La Rambla and over to Casa Calvet (Carrer de Casp, 48; 34-9/3412-4012). Gaudi’s most conventional building was once a textile manufacturer and a residence, and today the ground floor houses a popular restaurant. The wide avenue Passeig de Gràcia is home to two of Gaudi’s most famous buildings, the fanciful Casa Batlló(Passeig de Gràcia, 43; 34-9/3216-0306; casabatllo.es) and Casa Milà or La Pedrera (Provença, 261-265; 34-9/0220-2138; lapedrera.com). The next stop, La Sagrada Familia (Carrer de Mallorca, 401; 34-9/3208-0414; sagradafamilia.org), the sandcastle-like church that is famously still under construction, is less than a mile away. From there visitors can continue north to Park Güell(Carrer d'Olot, main entrance on Carrer de Larrard; 34-9/3409-1831; parkguell.cat)—originally conceived of as a housing development for well-to-do families, it was never fully realized and it became a public park in 1926. Two original homes still stand as well as an esplanade, an ornate stairway and a market hall all surrounded by gardens and parkland. On the way back pass by the Art-Nouveau Casa Vicens (Carrer de les Carolines, 18-24; casavicens.es), the first house designed by Gaudi. Closed to the public for many years, it will open in 2016 as a museum. While this can be done in a day, it's an ambitious itinerary, so consider breaking it up into two parts: Güell Palace, Casa Calvet, Casa Batlló, and Casa Milà on day one, and La Sagrada Familia and Park Güell on day two.