This is St. Stephen's Cathedral in Vienna (Stephansdom.) I was drawn (as you can see from the pictures) to the repetition of the ribbed vaults on the ceiling.
I love texture, lines, and repetition! Of course ribbed vaulting holds the building up, but normally I think it is the same color as the surrounding structure, therefore it blends in. The contrast here makes it an exciting visual element as well as a functional element in the church's architecture.
The look is even repeated on the back of this man. I'm not sure if this is for structural reasons (maybe someone out there can tell me.) It really is powerful for emotional reasons though. Poor guy! How would you like to hold all that up? And look, he is still looking up to the heavens, dutifully doing his job while still focusing on God!