Barcelona
Some possibilities here:
I think this is a likely one: http://www.tmb.net/en_US/turistes/busturistic/busturistic.jsp
{if that doesn't work try http://www.barcelonaturisme.com/ and select English)
http://www.barcelona-tourist-guide.com/en/tour/barcelona-bus-tour.html
http://www.frommers.com/destinations/barcelona/0045010008.html
One suggestion:
http://boards.cruisecritic.com/showpost.php?p=14109694&postcount=2
http://guides.travelchannel.com/barcelona