The eastern ends of the side galleries have been formed into separate chambers since the Turkish occupation. Of the additions beyond the original east wall of the church, that to the north was connected with the gallery by a tall wide arch, while that to the south was divided off from the gallery with only a small door as a means of communication. The southern addition was divided into two chambers as on the ground floor. The walls above gallery level and the large vaulting surfaces of the building are now covered with plaster, but a close examination proves that if any mosaic or marble revetment ever existed above gallery level, none of it, excepting the mosaic in the apse, remains. Looking next at the exterior of the building, it is to be observed that the ground on the north, south, and east has been raised as much as fifteen feet. In many places the walls have undergone Turkish repair. The apse shows three sides. The drum of the dome is pierced by twenty semicircular-headed windows (of which only five are now open), and as their arches and the dome spring at about the same level the heads of the windows impinge upon the dome's surface. Two low shoulders cover the eastern pendentives. The plan of the drum is peculiar. From the shoulders, just mentioned, to the windows, it is a square with rounded corners, one side of the square being joined with and buried in the drum of the western dome vault; but upon reaching the base of the windows it becomes an accurate circle in plan, and at the springing of the window arches is set back, leaving a portion of the piers to appear as buttresses. The upper portion of the drum is carried well up above the springing of the dome, leaving a large mass of material properly disposed so as to take the thrusts produced. The careful examination of the building by Mr. George has proved that the fabric is not the work of one age, but consists of parts constructed at different periods. For the full evidence on the subject we must await the forthcoming monograph on the church. Here, only the main results of Mr. George's survey can be presented. Up to the level of the springing of the aisle vaults, the walls of the main body of the building, excepting the narthex and the additions at the east end of the church, are built of large well-squared stones laid in regular courses, and are homogeneous throughout.