Also, if you have time/inclination, the core of streets behind the Cathedral are fascinating, and that's where a lot of the art galleries are (mostly painting though). If you have an interest, in a tiny little street in that area is a little synagogue museum, one of the few vestiges of Barcelona's Jewish history. The space itself dates back to at least the 1300's, and may even have been used as such as far back as late Roman/early Visigothic times. Blink and you'll miss it, so check your map carefully.