In Barcelona, you definitely have to visit the Sagrada Familia - one of Antoni Gaudi's works.
Also, a great day trip is hopping on a train early and heading to Figueres, a small town near the French-Spanish border known most prominently as the hometown of famous surrealist artist Salvadore Dali. Not surprisingly, Figueres is home to the largest Dali museum in the world – an absolutely fantastic view into the man’s insane mind. Even the building is an homage to the Dali style of bizarre meets extreme.
Mark