arcade is in alternate courses of one stone and two bricks, that of the upper portion has alternate courses of one stone and three bricks. Moreover, while the design of the upper portion is determined by the vaulting of the narthex, the lower portion takes a more independent line. These differences may indicate different periods of construction, but we find a similar type of design in other Byzantine buildings, as, for example, in the walls of the palace of the Porphyrogenitus, where the different stories are distinct in design, and do not closely correspond to one another. The outer narthex of S. Theodore may have been built entirely at one time, or its upper story, vaults, and domes may have been added to an already existing lower story. But in any case, notwithstanding all possible adverse criticism, the total effect produced by the façade is pleasing. It presents a noteworthy and successful attempt to relieve the ordinary plainness and heaviness of a Byzantine church exterior, and to give that exterior some grace and beauty. The effect is the more impressive because the narthex is raised considerably above the level of the ground and reached by a flight of steps. 'Taking it altogether,' says Fergusson,[425] 'it is perhaps the most complete and elegant church of its class now known to exist in or near the capital, and many of its details are of great beauty and perfection.' [Illustration: PLATE LXXI. S. THEODORE. THE CENTRAL DOME, FROM THE SOUTH.] [Illustration: S. THEODORE. THE WESTERN FAÇADE, FROM THE SOUTH. _To face page 246._] The esonarthex is in three bays covered with barrel vaults, and terminates at both ends in a shallow niche. The outer arches spring from square buttresses. From each bay a door conducts into the church, the central door being set in a marble frame and flanked by two Corinthian columns, which support a bold wall arcade.