Originally Posted by
fwoomp
If you're interested in architecture, you could visit one (maybe more) of the Gaudi sites--Sagrada Familia or one of the houses. I think you could probably find a Gaudi walking tour, with or without a guide.
And yes, eating good food is highly recommended!
You can see several Gaudi buildings if you walk up Passeig de Gracia from Plaza Catalunya to the Diagonal.