The five lower bays on the north side contain some of the oldest stained glass of the cathedral, installed in the old Romanesque cathedral in about 1180. When the nave was rebuilt in Gothic style in the 13th century, the old windows were reinstalled in random locations. In 1877, architect Gustave Klotz reconstituted the windows in their original arrangement. The windows are devoted to nine Emperors of the Holy Roman Empire. Each holds a sceptre in his right hand and an orb in the left hand, symbols of their responsibility as both sovereigns and religious figures. Some of the windows were assembled with glass from different periods: in the windows devoted to the Emperors Frederick II and Henry II of Bamberg, the heads were made between 1250 and 1275, but in 1522 were remounted onto the bodies of other kings from earlier windows made in about 1180. The small circular windows above the Emperors depict scenes from the life of Christ