Only the ground plan and the lower part of the western towers belong to the original building consecrated in 1110. The remainder was mostly finished by 1181, but the west choir and the vaulting were built in the 13th century, the elaborate south portal was added in the 14th century, and the central dome has been rebuilt.
The ornamentation of the older parts is simple; even the more elaborate later forms show no high development of workmanship. Unique sculptures depicting salvation stories appear above the Gothic-era south doorway. The baptismal font contains five remarkable stone reliefs from the late 15th century.
The cathedral is 110 m long, and 27 m feet wide, or including the transepts, which are near the west end, 36 m (inside measurements). The height in the nave is 26 m; under the domes it is 40 m.