In his admirable paper ‘Ravennatum Palatium Sacrum’ (Det Kgl. Danske Videnskabernes Selskab. Archaeologisk-kunsthistoriske Meddelelser 3, 2. Copenhagen, 1941) Dr. Einar Dyggve has revealed to us the type of the emperors' reception halls—la basilica ipetrale per ceremonie—in the late Roman empire. Analysing in a masterly way the famous mosaic of S. Apollinare Nuovo showing the Palatium of Theoderic, the missorium of Theodosius, the literary evidence for the Magnaura of Constantine, and architectural material, such as the palace of Diocletian in Spalato, from the fourth, fifth, and sixth centuries A.D., he defines a highly monumental tripartite architectural complex consisting of a tribunalium, also to be styled atrium or basilica discoperta, with a triumphal arch at its upper end, then a triclinium behind the atrium, and finally a most holy innermost absidal room, a choir.