If you life in Barcelona you quickly notice that Barcelona is a very special city. In Barcelona everything is special.
The aquarium for example. 15.50 EUR for a, well ok, it is big, shark basin, some very small fish tanks and a big gift shop (that you can enter without paying). In caixa's science museum you can see much more and the basic entrance of 3 EUR is surprisingly cheap (but you have to pay extra for almost everything you want to see).
Or the poble español (spanish village). 7.50 EUR to enter a shopping mall that is built like some houses in spanish cities. Don't expect something like a museum.
Finally, Night Life! Want to spend some hundreds of euros in one night? No problem in the center or on the beach, in the clubs and the discotheques. But yet close to the centre, in the Eixample, you may run into problems because the bars there close at 10 o' clock and thats it. Well, Barcelona is not Spain. Try not to forget it.
All in all, everything in Barcelona is special. Because it is in Barcelona.
PS: And don't get me started on the things they call "Tapas" here.