“…1a, Ill. 45). This is a real Classic "relic", today mounted in the doorway giving access to the so-called southern vestibule, in which the famous lunette mosaic with the emperors Constantine and Justinian was found and through which you can enter the narthex and the very heart of the building [39]. An important passage point for the visitors of the monument that however makes almost "transparent" the door itself [22; 23].…”