aachen cathedral unesco world heritage site with charlemagne's octagon and mosaics, north rhine westphalia, western germany

800 aachen aix aixlachapelle arches architecture building byzantine cathedral chandelier chapelle charlemagne church columns constructed cultural decorated emperor empire europe frankish franks germany heritage holy interior lavishly medieval mosaics nordrhein octagon oldest rhine rhinewestphalia rhineland roman romanesque saints site stonework style throne unesco west western westfalen westphalia world charlemagne#39aph39#s north marble arches columns