Everyone talks about the extraordinary catholic church La Sagrada Familia when they talks about Barcelona. This is actually one of the must-go attraction there but its building has been going under construction for a very very long time and I guess it's going to be like this until 2026... That's why I didn't pay to get inside because I was planning to go there again when the work's finished. Therefore, I am going to take you to see something else, some other architectures that you shouldn't miss while you are there.
If you are crazy about architecture, Barcelona is definitely a place for you. There is an alternative option for you to visit another great church which is Catedral de Barcelona. Although it ain't got a thing of the famous La Sagrada Familia, I still believe that it's a lovely church that you should really have a look.
There's two architectures that you should never miss, one is Casa Mila and the other one is Casa Batllo