From that time the order employed may be called the Neo-Byzantine. This was a decline of art as much as the history of Greece and the Eastern Empire during the same period (about 600 to 1453) was the history of the decline and extinction of a power that had once been as great among governments as St. Sophia (Fig. 94) was among churches. [Illustration: FIG. 94.--CHURCH OF ST. SOPHIA. _Constantinople. Exterior View._] The chief characteristic of Byzantine architecture is the use of the dome, which is the most important part of its design. A grand central dome rises over the principal portion of the edifice, and just as in other orders courts and colonnades were added to the simpler basilica form in the ground plan of the churches, so in the Byzantine order lesser domes and cupolas were added above until almost any number of them was admissible, and they were placed with little attention to regularity or symmetry of arrangement. [Illustration: FIG. 95.--LOWER ORDER OF ST. SOPHIA.] As domes were the chief exterior feature, so the profuse ornamentation was most noticeable in the interior. The walls were richly decorated with variegated marbles; the vaulted ceilings of the domes and niches were lined with brilliant mosaics; the columns, friezes, cornices, door and window-frames, and the railings to galleries were of marbles, and entirely covered with ornamental designs (Figs. 95 and 96). [Illustration: FIG. 96.--UPPER ORDER OF ST. SOPHIA.] The historian Gibbon describes the building of St. Sophia and its decorations. He tells us that the emperor went daily, clad in a linen tunic, to oversee the work. The architect was named Anthemius; he employed ten thousand workmen, and they were all paid each evening. When it was completed and Justinian was present at its consecration, he exclaimed, "Glory be to God, who hath thought me worthy to accomplish so great a work; I have vanquished thee, O Solomon!" Paul Silentiarius was a poet; he saw St. Sophia in all its glory and describes it with enthusiasm. It was very rich in variegated marbles. He mentions the following: 1. _The Carystian_, pale with iron veins. 2. _The Phrygian_, two sorts, both of a rosy hue; one with a white shade, the other purple with silver flowers. 3. _The Porphyry of Egypt_, with small stars. 4. _The green marble of Laconia._ 5. _The Carian_, from Mount Iassis, with oblique veins, white and red. 6. _The Lydian_, pale, with a red flower. 7. _The African or Mauritanian_, of a gold or saffron hue. 8. _The Celtic_, black, with white veins. 9. _The Bosphoric_, white, with black edges. There were also the _Proconnesian_, which made the pavement; and the _Thessalian_ and _Molossian_ in different parts. This array of marbles was made even more effective by the beautiful columns brought from older temples. The mosaics were rich in color, and numerous, and many parts of the church were covered with gold, so that the effect was dazzling.