Camp Nou football stadium tour. Even if you're not a footy fan, it's a good tour just to see all the silver work. Casa Mila, Casa Batlo, Sagrada Familia all worth a look. El Corte Ingles store has about 5 floors of goodies and is wonderfully air conditioned when it's hot outside. City tour - hop on, hop off bus. Get a two day ticket as there are a few routes that take in the city sights so you can go back and see things in more detail the next day. Brilliant city so you'll have a great time.