Speaking of the most famous church in Barcelona, Spain the Sagrada Familia is a UNESCO World Heritage Site designed by Catalan architect Antoni Gaudi. This roman catholic church is the most extraordinary personal interpretation of Gothic architecture since the middle Ages.
Basilica and Expiatory Church if the Holy Family is a large Roman Catholic church in Catalonia, Spain. It is still incomplete but was already consecrated by Pope Benedict XVI on November 2010. I was really amazed by the its structural wonder, truly one of a kind. I know lot of Catholics would really love to see this church and definitely a must see travel spot when you visit Barcelona.