Theophanes,[301] the earliest writer to mention the church of the Diaconissa, ascribes its foundation to the Patriarch Kyriakos (593-605) in the fourth year of his patriarchate, during the reign of the Emperor Maurice. According to the historical evidence at our command, that church was therefore erected towards the close of the sixth century. Dr. Freshfield,[302] however, judging by the form of the church and the character of the dome, thinks that Kalender Haneh Jamissi is 'not earlier than the eighth century, and not later than the tenth.' Lethaby[303] places it in the period between Justinian the Great and the eleventh century. 'The church, now the Kalender mosque of Constantinople, probably belongs to the intermediate period. The similar small cruciform church of Protaton, Mount Athos, is dated c. 950.' Hence if Theophanes and his followers are not to clash with these authorities on architecture, either Kalender Haneh Jamissi is not the church of the Diaconissa, or it is a reconstruction of the original fabric of that sanctuary. To restore an old church was not an uncommon practice in Constantinople, and Kalender Haneh Jamissi has undoubtedly seen changes in the course of its history. On the other hand, Diehl is of the opinion that the building cannot be later than the seventh century and may be earlier.[304] [Illustration: PLATE XLVII. (1) S. MARY DIACONISSA. THE INTERIOR, LOOKING NORTH-EAST. (2) S. MARY DIACONISSA. THE INTERIOR, LOOKING SOUTH-EAST. _To face page 184._] _Architectural Features_ The church belongs to the domed-cross type. The central area is cruciform, with barrel vaults over the arms and a dome on the centre. As the arms are not filled in with galleries this cruciform plan is very marked internally. Four small chambers, in two stories, in the arm angles bring the building to the square form externally. The upper stories are inaccessible except by ladders, but the supposition that they ever formed, like the similar stories in the dome piers of S. Sophia, portions of continuous galleries along the northern, western, and southern walls of the church is precluded by the character of the revetment on the walls. In the development of the domed-cross type, the church stands logically intermediate between the varieties of that type found respectively in the church of S. Theodosia and in that of SS. Peter and Mark.