From the airport
Train: Take the R2N to Passeig de Gracia.
Taxi: It's a 20-30 minute trip and costs around €35.
Metro: Take L9 Sud to Torassa, There, change to L1 and alight at Catalunya.
Aerobus: Shuttle service connecting the airport to the center of Barcelona. It drops you off at Plaza Catalunya and runs every 5 minutes. Estimated journey time is around 35 minutes.