Barcelona's Ciutat Vella (Old City) is the place to be if you're looking for a fun, exciting and action packed night on the town. Between the rustic Raval, trendy Born and popular Gotico neighborhoods, there are more bars and nightclubs than most people know what to do with. Depending on what you're looking for, there are a variety of late night options as well including after hour bars, which are usually open until 2 or 3pm the next day - if you can last that long.
In terms of great clubs, some prime areas to consider scoping out include Plaza Reial in the Gothic Quarter, right off La Rambla, Passeig Del Born in the Born neighborhood and Rambla Del Raval in the Raval. Plaza Reial is home to an abundance of night clubs and even if you don't feel like going inside the clubs, the square itself is a lot of fun to spend time in as it's always packed and full of eclectic characters, especially on Friday and Saturday evenings. Another great area of Ciutat Vella to explore is on the edge of Barceloneta neighborhood. Some of the fanciest and most well known clubs are situated along the boardwalk including Shoko, Cat Walk and the CDLC. So no matter where you end up in Ciutat Vella, you'll never be left without a lively nightclub at your fingertips.