The Justinian period commences with the beginning of the sixth century. It is characterised by the development of the drumless dome on pendentives. The plan is complicated, and the buildings are large in comparison with those of later date. To this period belong SS. Sergius and Bacchus (527 A.D.), the baptistery of S. Sophia, and the 'Great Church' of S. Sophia itself. S. Andrew in Krisei and S. Saviour in the Chora probably date from this period. The carved detail of the former closely resembles that of SS. Sergius and Bacchus, and the plan of the latter connects it with S. Sophia, Salonica (sixth century). The Justinian period roughly includes the seventh century, and is followed by a long decline, marked by the great iconoclastic controversy which lasted almost until the middle of the ninth century. To this period belongs S. Irene (740 A.D.). In plan it is a double-domed cross church. In the arrangement of the dome-arches and galleries it resembles S. Theodosia, whilst in the presence of a western gallery over the narthex and in the number of columns in the 'nave arcade' it is like S. Sophia. The accession of Basil the Macedonian (867 A.D.) marks the beginning of the second great period--the 'Basilian Renaissance.' We know that this was a period of great religious activity, and though we have, unfortunately, no known dates to guide us, the development of plan leads us to place a group of churches in the ninth, tenth, and eleventh centuries. These are S. Mary Pammakaristos, S. Mary Panachrantos, S. Theodosia, S. Mary Diaconissa, and SS. Peter and Mark. They are all churches of considerable size; S. Mary Diaconissa and S. Theodosia being indeed large. They are characterised by the use of the ambulatory and domed cross plans. The carving is coarse and the capitals are of the clumsy Byzantine Corinthian type. The dome is raised on a high drum in S. Mary Pammakaristos and S. Mary Panachrantos, though this may be a later addition. The domes of the other three churches seem to be Turkish. S. Mary Pammakaristos and the south church in S. Mary Panachrantos are identical in plan with S. Andrew in Krisei, and it would be possible to date them earlier had we any evidence whatsoever. Unfortunately both have been very much altered. S. Theodosia, S. Mary Diaconissa, and SS. Peter and Mark, taken in this order, form a series showing the gradual disappearance of the galleries and the evolution of the domed cross church into the 'four columned' church of the next period.