start=Construction began on the northern window in about 1160, and the window was finished about 1250. The Cathedral itself took all the way into the mid 1300s. The window is constructed in strict gothic style, which is denoted by having its jambs recessed into the wall as opposed to protruding. The northern and western rose windows are very unique in the fact that they still have most of their original glass intact. Whereas most of the rest of the cathedral has undergone countless renovations. The northern window is about 33 meters wide, and contains over 2500 individual pieces of colored glass.