Originally Posted by Ross

Go check out Sagrada Familia, it is absolutely stunning. I recommend doing the hop on, hop off bus tours of the city too, it's a great way to get around all the best sights. If you combine a 2 day pass, it works out cheaper and you can do all 3 routes, I think. I did it and it was great, you get to the Camp Nou and can take the tour then hop back on the bus and head to the next destination.