Santa Maria de Montserrat
This can be done as a side trip from Barcelona, but AlteCocker did it from Salou. This is a fabulous place even if you are not Roman Catholic. AlteCocker is a Jew by background, but is not religious. Even so, she was moved by the place. If you take a package tour, there is no need to do one that goes anywhere but Montserrat as there is plenty for you to do for the 5-6 hours you will spend there. It is the beating heart of Catalonia. It was AlteCocker's favorite site of her August 2015 home exchange in the area.