The Basilica and Expiatory Church of the Holy Family, is one of the most significant buildings in Spain and possibly a lot of elsewhere too. Started in 1882, it is still undergoing construction and is a truly monumental undertaking in every sense. There are certain great works of art that pictures cannot do justice to, you have to be with them to understand that something very special is going on. This is one of them. It is still a controversial building and at the risk of being a very broad and simplistic generalisation, I think it boils down to whether you prefer organic structures and processes, or postmodern glass and steel boxes. There are many religious structures in the world but relatively few have a genuinely holy feeling but even in its unfinished state and despite the tourist throng, the Sagrada Familia manages to engender a sense of awe and mystery. (See also the Kirche am Steinhof in Vienna)