Barcelona's El Prat de Llobregat Airport, 7 km (4½ mi) south of the city, receives international flights from all over the world. Low-cost flights such as Ryanair land in Girona, an hour north of Barcelona. Getting to the city from the airport is easiest by taxi (EUR 20-EUR 28), but the bus to Plaça Catalunya (EUR 4.95) leaves from directly in front of each terminal and is about as fast as a taxi—and a fraction of the cost. From Plaça Catalunya a taxi to your hotel (EUR 5-EUR 10), can be easily flagged down.
Long-distance trains arrive and depart from Estació de Sants. En route to or from Sants, some trains stop at another station on Passeig de Gràcia at Carrer Aragó; this can be a good way to avoid the long lines that form at Sants during holidays, though even better is dealing directly with www.renfe.es. For schedules and fares, call RENFE at 902/240202.
For trips outside of town, car rental agencies in Barcelona are at the airport and at Sants train station. Within the city, a car is more liability than asset; you're better off with taxis, your feet, the metro, or the bus.