The great Church of the Holy Wisdom, known as Hagia Sofia or Sancta Sofia, in Istanbul, is the high point of Byzantine ecclesiastical architecture, remarkable for its revolutionary dynamic structural system and the ingenuity of a plan that subordinates liturgy to form. It was dedicated by the Byzantine emperor Justinian in December 537. Like many churches, it was built on the site of former sacred structures, some of which predated Christianity. The earliest church had been replaced in 361 by the timber-roofed basilica Megala Ekklesia. Damaged during religious riots in 404, this second building was restored eleven years later under Emperor Theodosius II, only to be burned down in another uprising in 532. Within weeks Justinian commissioned the great church of Hagia Sofia.
He had been, crowned in 527. Despite the fall of the Western Empire to Germanic invaders in the late fifth century, Justinian ensured that his Eastern Empire survived. He and his wife, Theodora, reigned as unofficial joint rulers, together transforming Constantinople into a city that was universally admired and envied. Justinian employed the architects Anthemios of Tralles and Isidor of Miletus to build a church of great size and magnificence, sparing no expense. Materials were transported from all over his domain. Dressed marble was plundered from classical pagan buildings; it is said that eight red porphyry columns were brought from the Artemiseion at Ephesus; new stone came from the finest marble quarries in Phrygia, Egypt, Thessaly, and the Morean Peninsula. The interiors were decorated with mosaics of gold, silver, glass, marble, and granite tesserae. Because of the urgency, tradition has it, 1,000 masons and 10,000 apprentices worked on the building. It was completed in just twenty days under five years. There is a story, perhaps apocryphal, that upon, first visiting the completed church Justinian exclaimed. “Oh Solomon! I have excelled you!”
The central dome, framed with forty brick ribs, is slightly elliptical, its base measuring 101 by 104 feet (30.3 by 31.2 meters). It springs from pendentives at 183 feet (54 meters) above the floor and rises to 226 feet (67.8 meters). There is a window between the bases of each pair of ribs, and the resulting ring of light creates the illusion that the dome is poised in the air with little apparent support. The true massiveness of the masonry structure is replaced with a virtual building created from light—not only because the penetrating rays of the sun constantly change in angle and direction, but also because of the scintillation of the mosaic-covered surfaces as the light skips from facet to facet.
Awesome in size and opulent in finish though it was, it is not for these reasons that Hagia Sofia is an architectural feat. It is because of its structural brilliance and the subtlety with which the spaces are articulated—underlining the difference between the practical directness of Western architecture and the nuances of oriental. Nevertheless, the church remains Roman. The subdivision of its spaces according to their purposes coincides with contemporary Western basilicas: atrium, narthex, nave and aisles, sanctuary, apse, vestries, and altar are all present.
There the similarity ends. Western churches were long and narrow, and their slender parallel walls supported timber-framed roofs. The plan of Hagia Sofia is almost square, approximately 250 by 220 feet (75 by 67 meters), and the four massive piers, each about 25 by 60 feet (7.6 by 18.3 meters), carry a domical roof. Yet when the spatial arrangement of the church is considered, it can be readily seen that by the use of elegant screens to separate aisles and nave, and the placing of the apse, the architects skillfully manipulated a vast single space to meet the liturgical program of the clergy. The interior space is made cruciform by projecting a large hemidome over the apse and smaller ones above the aisles. This daring experimentation with space was made possible through the use of the pendentive, a structural device that allowed Byzantine architects to satisfactorily roof a cubical volume with a dome. That had never been achieved in the West, and never before on such a scale in the East, from whose vernacular architecture it had been drawn.
Hagia Sofia has undergone many changes in its 1,500-year lifetime, with both natural forces and desecration taking their toll. The church was structurally damaged by earthquake only a year after its dedication, and again in 557 and 559. In 562 it was restored and reinforced by Isidoros, nephew of the original architect, who also raised the dome by about 20 feet (6.25 meters). Further earthquake damage in 869 and 889 closed it for five years. The Iconoclasts vandalized the original mosaics in the eighth and ninth centuries, but most were replaced. Hagia Sofia’s finest ornaments were plundered by the Fourth Crusade in 1204, and the building was seriously damaged. Large buttresses were added to the north and south facades in 1317, but that did not prevent considerable earthquake damage about thirty years later. Mehmet the Conqueror took Istanbul for Islam in 1453, and Hagia Sofia, although retaining its name, was put to use as a mosque. Large timber medallions with Koranic texts were hung on the walls of the interior and the Christian mosaics whitewashed over. Minarets were added at various times during the Ottoman period. The building became a museum in February 1935.
At the end of the twentieth century Hagia Sofia stood on the United Nations World Heritage Watch List, one of the world’s 100 most threatened buildings. “Despite … ongoing support, including a grant [$100,000 in 1997] from American Express, water penetration, tourist control, and uncertain structural conditions remain threats. Areas of the lead roof have cracked, roofing members have weakened, and leaks are damaging frescoes and mosaics.” Restoration and repairs of the roof have been effected, but more money is needed to prevent further structural damage and to install a long-term dilapidation monitoring system.