A Literary and Structural Analysis of the First Dome on Justinian's Hagia Sophia, Constantinople

Many scholars have speculated on the shape of the first great dome on Justinian's Hagia Sophia, which was demolished in 558 after a partial collapse the year before. Rowland Mainstone has suggested that it was a shallow structure, anchored directly to the upper cornice at the culmination of the pendentives. His basis for assuming this profile is John Malalas's testimony that the new dome was constructed 20 feet higher than the first dome, which would thereby have been a full two-fifths shallower than its replacement. By accepting Malalas's testimony almost too eagerly, modern scholars subvert the eyewitness account in Procopius's The Buildings, which makes clear reference to a "rounded structure" resting on the main arches and standing below the dome itself. Such a structure, which according to Procopius contain the dome's windows, can only be interpreted as a drum. Procopius refers in almost identical terms to the central dome of the Church of the Holy Apostles in Constantinople, taking pains to draw a parallel here with the drum of Hagia Sophia. Both churches, he attests, have this same "circular structure" resting upon the arches and penetrated by the windows. A later literary source confirms that the Holy Apostles did indeed have drums under its five domes, and most prominently under the central dome. If St. Sophia's drum accommodated the full height of the windows, and provided sufficient headroom for persons walking upon the cornice, it might well have been ten feet high or more. Malalas's 20-foot differential, if it is reliable in the first place, is not violated by this hypothesis; for it could refer simply to the relative depths of the first and second domes, while ignoring the lesser change in elevation implied by raising the first, shallower dome on a drum.