May 27-30. This is the 15th year of the festival, and has an international lineup that boasts the top in rock, electronica, hip-hop and much more. 

A weeklong festival with no overnight camping, Primavera is similar to Lollapalooza or Outside Lands in that you have a chance to explore your host city. Music starts daily around 3pm and goes laaaate into the wee hours. Depending on your night before, you feasibly could spend a lot of time getting to know Barcelona. The festival vibe matches that of the city, and the crowd is more laid back than some of its European and American counterparts.

Once you get those plane tickets booked, head on over here. Barcelona in the spring? Yes, please.