Let me just say this - doing a bike tour in the country and doing a bike tour in a city - 2 totally different things! Not only was it a challenge trying to veer around pedestrians and cars, but the other people on the excursion were the biggest challenge. I don't think that some of those people had been on a bike in decades - they made for a very frustrating ride through the city.
Otherwise - the sites were amazing. We rode through the city, visiting the various squares and amazing works of architecture. My favorite part was riding through the Olympic Village and seeing the rows of flagpoles from the 1992 Olympics.
Here is the link to the Barcelona pictures: