Whilst Madrid was under siege Barcelona and Catalonia were aslo the scenes of important battles. A personal account of the fighting here was given by George Orwell in one of his best known novels Homage to Catalonia.
Spanish Sites is aware of two web sites offer tours, more information in English about Orwell, the International Brigades and the civil war in Catalonia.
http://iberianature.com/barcelona/history-of-barcelona/spanish-civil-war-tour-in-barcelona/ Nick Lloyd has lived in Spain for 20 years and offers guided tours about Barcelona in the civil war. The 3 hour or all day visits are by appointment and will lead you to the key areas of interest with a full explanation in English. Nick’s book about his tours in Barcelona can be ordered here.
http://pdlhistoria.wordpress.com/ Alan Warren is a historian and publisher of books about the civil war and the International Brigades. The tours are by appointment and cover the battle of the Ebro beyond Barcelona.