The beauty of this UNESCO-listed cathedral resides in its architectural unity. Most of the building was completed in a short time (1095-1133); despite later additions and renovations the building has retained its harmony. The cathedral dominates the palace square, the university buildings surrounding it and the castle. The solemn majesty of the nave is enhanced by the two 13C west towers, the 15C central tower (66m) and, to the east, the flying buttresses supporting the Nine Altars Chapel.