Barcelona is an embarrassment of riches in the photography department. If you like street, take your camera and stroll down Las Ramblas... just the street performers alone are worth it. The architecture is amazing, especially the buildings Gaudi designed like Sagrada Famila and Guell (the park). In the Gothic quarter there is a cathedral (I forget the name) that you could easily spend a day at by itself. Enjoy your trip and please post some of your pictures!