Consisting of parts and pieces of four separate building phases, the Gereon is practically the Romanesque church equivalent of a collage. The main oval structure dates all the way back to the 4th century, and the careful additions made in the 11th, 12th, and 13th led the project to be compared, in kind and in quality, to the Hagia Sofia in Istanbul.
Gereonskloster 2, Cologne, Germany