If you don’t have any plans for today you should consider going to the Emergència independent music festival in CCCB. The CCCB is the contemporary culture center in Barcelona, and every year they organize a lovely little festival with indie bands from Spain and from elsewhere, too. It starts early (doors open at 17:00, first band plays at 18:00) and that is one of the charms with the festival, along with the location. It finishes at around midnight. The tickets are cheap, 7 €, so you have no excuse!