I'm pretty sorted for my days.

Friday - wander round and see all the Gaudi buildings and the Parc De La Ciutadella
Saturday - trip to Montserrat first thing. Come back in time to walk up to Montjuic Castle
Sunday - walking tour

I have no plans for the evenings though. I'm going on my own, so hoping I meet some people at the hostel I'm staying at who want to go out and do shit, but if not, what evening things would people recommend? Basically, as it's December it's going to be dark a lot. What are the best things to do in Barcelona when it's cold and dark?

I'm staying in the Be Sound hostel, so pretty central.

Thanks!