The best way to get around Barcelona is on foot; the occasional resort to subway, taxi, or tram will help you make the most of your visit. The comfortable FGC (Ferrocarril de la Generalitat de Catalunya) trains that run up the center of the city from Plaça de Catalunya to Sarrià put you within 20- to 30-minute walks of nearly everything. (The metro and the FGC close just short of midnight Monday through Thursday and Sunday, and at 2 am on Friday; on Saturday, the metro runs all night. The main attractions you need a taxi or the metro to reach are Montjuïc (Miró Foundation, MNAC, Mies van der Rohe Pavilion, CaixaFòrum, and Poble Espanyol), most easily accessed from Plaça Espanya; Park Güell above Plaça Lesseps; and the Auditori at Plaça de les Glòries. You can reach Gaudí’s Sagrada Família by two metro lines (L2 and L5), but you may prefer the walk from the FGC’s Provença stop, as it’s an enjoyable half-hour jaunt that passes by three major Moderniste buildings: Palau Baró de Quadras, Casa Terrades (les Punxes), and Casa Macaia.
Sarrià and Pedralbes are easily explored on foot. The Torre Bellesguard and the Col.legi de les Teresianes are uphill treks; you might want to take a cab. It’s a pleasant stroll from Sarrià down through the Jardins de la Vil.la Cecilia and Vil.la Amèlia to the Cátedra Gaudí (the pavilions of the Finca Güell, with Gaudí’s amazing wrought-iron dragon gate); from there, you can get to the Futbol Club Barcelona through the Jardins del Palau Reial de Pedralbes and the university campus, or catch a two-minute taxi.
All of Ciutat Vella (Barri Gòtic, Rambla, El Raval, Born-Ribera, and Barceloneta) is best explored on foot. If you stay in Barceloneta for dinner (usually not more than €25), have the restaurant call you a taxi to get back to your hotel.
The city bus system is also a viable option—you get a better look at the city as you go—but the metro is faster and more comfortable. The tramway offers a quiet ride from Plaça Francesc Macià out Diagonal past the Futbol Club Barcelona and beyond to Cornellà and Sant Feliu de Llobregat, or from the Vila Olimpica terminus in Poblenou, behind the Ciutadella Park, out to Glòries and the Fòrum at the east end of Diagonal, continuing on across the Besòs river to neighboring Sant Adrià.