Joseph Lins, Catholic Encyclopedia (1913) — Aachen (1913)
“ Over the spot supposed to be the site of Charlemagne's grave hangs an enormous corona of lamps, the gift of the Emperor Frederick I, Barbarossa; in the choir of the octagon, the so-called upper minster, stands Charlemagne's throne, made of great slabs of white marble, where, after the coronation, the German emperors received the homage of their nobles. ”
