You can't visit Barcelona without eating any tapas. You simply can't. There are so many places offering this typical Spanish speciality. The problem is not about finding one, it's more about finding the right one, I mean the best one, like the Cervecería Catalana restaurant, located on the Mallorca street. Tapas are not only fresh and well-presented, they are excellent too!
The place will probably be full when you arrive. That's fine. Just have a glass and wait until you get a table! Or make that two!