Detail of the gallery of the Palatine Chapel. The columns are purely decorative, not bearing any weight of the arches. Charlemagne had 32 of them shipped from the ancient buildings of Rome and Ravenna. Most of them were looted in the French Revolution but 22 have since been returned and restored to their place in the gallery.
The grilles between the pillars were cast of bronze under orders of Charlemagne for this cathedral. They have elaborate patterns that indicate Roman, Celtic and Frankish influences, and are matched in pairs across from each other.