This is a narrow passage that in Byzantine times was called the Vestibule of the Warriors. According to a Book of Ceremonies, a manual of Byzantine court-ritual, the Emperor removed his sword and crown before entering the narthex, his bodyguards would wait here until he returned. The great mosaic above the entrance is often overlooked by visitors, as it now functions as exit. The other mosaics to a large extent also are from the Justinian church.

There also is a wonderful door, taken from a Hellenistic temple, so older than the building itself.