The capitals are of the 'Pseudo-Ionic' type, with roughly cut Ionic volutes. The sinking on their lower bed is too large for the necks of the columns. Towards the aisles they bear the monograms of Justinian and Theodora, identical with the monograms of these sovereigns in S. Sophia, while on the side towards the nave they have a cross in low relief. Usually monograms are placed in the more conspicuous position.
Above the capitals the vaulting that covers the aisles and supports the galleries is of an uncommon type. Towards the nave the arches are narrow and raised upon very high stilts; from each capital a semicircular arch is thrown across to the outer wall, where is a range of windows, each of which has an extrados at a slightly higher level than the extrados of the corresponding nave arch; and thus a long narrow space is left between the four arches of each vault compartment that could be filled, wholly or in part, without the use of centering. The result is a narrow, irregularly curved vault, shaped to the backs of each of its surrounding arches, and having, in the main, the character of a spherical fragment.
The western portion of each aisle is divided from the nave by an irregular arcade supported by a pier and one column, and, consequently, there are three aisle bays to the western nave bay, and not four as shown by Salzenburg.
The whole interior surfaces of the walls, up to the level of the springing of the gallery vaulting, and the nave walls, up to the gallery level, were once faced with marble. This is proved by the presence in the walls of many marble plugs and some iron holdfasts, as well as by remains of the moulded base of the facing.
At the eastern extremity of the aisles there are chambers formed by walls built, as the vertical straight joints and difference of materials employed indicate, at various periods. The chamber at the end of the northern aisle has an archway, now built up, in its eastern wall, and seems to have served as a vestibule. It is in these chambers that Salzenberg supposes the staircases leading to the galleries stood, but it is evident from the character of the walls and vaulting that no such staircases could ever have existed there.