Barcelona is a city rich in history, architecture and of course art. It's renowned for being home to some of the most well known artists, including Pablo Picasso, Joan Miro and just a little up the coast, Figueres was home to Salvador Dali. Even if you're not a 'museum goer' by nature, Barcelona has a diverse variety of historical as well as fun and inspiring venues to ignite your passion even more for the city. With several of the more interesting ones situated in the Old City (Gotico, Born, Barceloneta) there are also a few really cool museums just a short ride outside the city center, which is great if you want to combine your museum experience with being able to take in the sites as well as gorgeous panoramic views. Most of the museums don't require reservations, but it never hurts to arrange for tickets ahead of time online, as it really saves you time standing in line, especially for some of the more popular ones like the Picasso Museum which can see lines of up to an hour during high season.
One of the newest additions to the Museum scene is the Ideas Museum which is definitely worth a look, right off of Plaza Sant Jaume in the Gothic Quarter.