text: Symbolism Odo of Metz applied the Christian symbolism for figures and numbers. The building was conceived as a representation of the heavenly Jerusalem, the Kingdom of God, as described in the Apocalypse. The outer perimeter of the cupola measures exactly 144 Carolingian feet whereas that of the heavenly Jerusalem, ideal city drawn by angels, is of 144 cubits. The mosaic of the cupola, hidden today behind a 19th-century restoration, showed Christ in Majesty with the 24 elders of the Apocalypse. Other mosaics, on the vaults of the aisle, takes up this subject by representing the heavenly Jerusalem. Charlemagne's throne, located in the West of the second floor, was placed on the seventh step of a platform.
  Other buildings
  Treasury and archives
  The treasury and archives of the palace were located in a tower tied to the great hall, in the North of the complex. The chamberman was the officer liable for the rulers' treasury and wardrobe. Finance administration fell on the archichaplain, assisted by a treasurer. The treasury gathered gifts brought by the kingdom's important people during the general assemblies or by foreign envoys. This made up an heterogeneous collection of objects ranging from precious books to weapons and clothing. The king would also buy items from merchants visiting Aachen.
  The chancellor was liable for the archives. The chancellery employed several scribes and notaries who wrote down diplomas, capitularies and royal correspondence. Agents of the king's offices were mostly clergymen of the chapel.