The Byzantine Church of Hagia Sophia stands atop the first hill of Constantinople at the tip of the historic peninsula, surrounded by the waters of the Sea of Marmara, the Bosphorus and the Golden Horn on three sides. It was built by Justinian I between 532 and 537 and is located in close proximity to the Great Palace of the Emperors, the Hippodrome, and the Church of Hagia Irene. The third known church to be built at its site since 360, the Justinian church replaced the smaller basilica built by Theodosius II in 415, which burnt down in the Nika riots against Justinian I and Empress Theodora. Beginning construction immediately after suppressing the revolt, Justinian commissioned physicist Isidoros of Miletus, and mathematician Anthemios of Thrales (today's Aydin) to build a church larger and more permanent than its precedents to unify the church and reassert his authority as the emperor. There is little that remains from the earlier churches beside the baptistery and the skeuophylakion. The skeuophylakion, a round building that houses the patriarchal treasure, is located off the east corner and the baptistery, which was converted into an Ottoman tomb in 1639, stands to the southwest.
The grand dome of the Hagia Sophia, an impressive technical feat for its time, is often thought to symbolize the infinity of the cosmos signified by the Holy Soul to which the church was dedicated. A series of earthquakes that shook Istanbul in 557 eventually caused the collapse of central dome in May, 558. Construction of a taller dome, braced with forty ribs, took 5 years. This dome was more stable, only necessitating partial rebuilding after it was damaged in the earthquakes of 859 and 989. Plundered during the Latin invasion following the Forth Crusade in 1204, the church was restored under Andronicos II during Palaeologan rule. The great southeast arch was reconstructed after the 1344 earthquake. As the Cathedral of the Ecumenical Patriarchate of Constantinople for over a thousand years, with the brief exception of the Latin occupation, the Hagia Sophia was the center of Eastern Christianity from 360 to the Ottoman conversion. Its importance as the center of religious authority in the Byzantine capital was compounded with its role as the primary setting for state rituals and pageantry. The Ottoman conquest of Constantinople in 1453, which put an end to the Byzantine Empire, began the era of Islamic worship in the holy structure, which Mehmed II converted into a mosque immediately after his conquest.
Known then on as the Ayasofya Mosque, the Hagia Sophia remained the Great Mosque of the Ottoman capital until its secularization under the Turkish Republic In 1934. Little was modified during the initial conversion when a mihrab, a minber and a wooden minaret were added to the structure. Mehmed II built a madrasa near the mosque and organized a waqf for its expenses. Extensive restorations were conducted by Mimar Sinan during the rule of Selim II; the original sultan's lodge was added at this time. Mimar Sinan built the Tomb of Selim II to the southeast of the mosque in 1577 and the tombs of Murad III and Mehmed III were built next to it in the 1600s. Mahmud I, who ordered a restoration of the mosque in 1739, added an ablution fountain, Koranic school, soup kitchen and library, making the mosque the center of a social complex. Perhaps the most well known restoration of the Hagia Sophia was completed between 1847-49 during the rule of Abdülmecid II, who invited Swiss architects Gaspare and Guiseppe Fossati to renovate the building. In addition to consolidating the dome and vaults and straightening columns, the two architects brothers revised the decoration of the exterior and the interior. The discovery of the figural mosaics after the secularization of Hagia Sophia, was guided by the descriptions of the Fossati brothers who uncovered them a century earlier for cleaning and recording. An earlier record of the Hagia Sophia mosaics is found in the travel sketches of Swedish engineer Cornelius Loos from 1710-1711.
The period of systematic study, restoration and cleaning of Hagia Sophia, initiated by the Byzantine Institute of the United States and the Dumbarton Oaks Field Committee in the 1940s, still continues to our day. Archaeological research led by K. J. Conant, W. Emerson, R. L. Van Nice, P.A. Underwood, T. Whittemore, E. Hawkins, R. J. Mainstone and C. Mango have illuminated different aspects related to the history, structure and decoration of the Justinian church. A. M. Schneider and F. Dirimtekin after him have excavated remains of the earlier churches outside the Justinian church. A colloquium convened at Princeton University in 1989 has led the way towards a computer-based structural modeling of the church directed by Prof. A. Çakmak. This work has provided the basis for a new restoration project underway since 1995 that focuses on structural monitoring to gauge long-term stability of the structure along with historical restoration. The Hagia Sophia was included in the annual list of 100 most endangered monuments published by the World Monuments Fund in 1996 and in 1998, to secure funds for continued work. Considered a significant influence on the conception of classical Ottoman architecture, the Hagia Sophia is open to visitors as a public museum.
The Architecture of the Hagia Sophia
The Hagia Sophia is a domed basilica, oriented on the northwest-southeast axis. Entered from the northwest through an outer and inner narthex, the church consists of a rectangular nave flanked by an aisle and gallery on the sides and an apsidal sanctuary, projecting southeast.
Each narthex comprises nine cross-vaulted bays; the narthexes were originally preceded by a large atrium enclosed by a colonnade, portions of which were still standing in the 1870s. The inner narthex is taller than, and about twice as wide as, the outer narthex, and has a second level linked to the nave galleries. It is lit by a row of clerestory windows to the northwest. Passages attached to either end of the inner narthex give access to the gallery. The passage to the southwest also served as the ceremonial entrance for emperors; its entryway is adorned with a pair of elaborate bronze doors with 9th century monograms. Its inner door has a 10th century mosaic in its lunette depicting Emperors Constantine and Justinian offering models of Constantinople and Hagia Sophia to enthroned Virgin and Christ. While the outer narthex is largely devoid of decoration, the walls of the inner narthex are lined with polychrome marble panels and bordered by a deep continuous frieze and its vaults are adorned with mosaics with geometric motifs and crosses on a gold background.
Nine doors lead from the inner narthex into the nave. The tall entryway at the center is called the Imperial Door and is crowned by a mosaic depicting an emperor prostrating before Christ Pantocrator, flanked by portraits of the Virgin and Archangel Gabriel. The nave is roughly twice as long as it is wide without the flanking galleries and it measures 73.5 meters long and 69.5 meters wide including the galleries. It has four niches at the corners, which are carved into the aisle and galleries. A grand dome, raised 56 meters from the ground, crowns the nave. Its forty windows, located between supporting ribs at the base, give the impression of floating. At its apex, originally adorned with a mosaic of Christ Pantocrator, is a calligraphic medallion quoting the Light Verse (24:35), inscribed by Mustafa Izzet Efendi during the Fossati restoration. The weight of the dome is carried on pendentives and four colossal piers, which are connected by arcades separating the aisle and galleries. The aisle is significantly taller than the galleries, where the intercolumnal width has been kept smaller to maintain the proportion. To the northwest and southeast, single arches braced by large semi-domes receive the lateral loads and distribute it to three smaller semi-domes that crown the nave niches and - to the southeast - the sanctuary apse.
The length of clear span afforded by the combination of the central dome and the semi-domes was unprecedented at the time of Hagia Sophia's construction. To the northeast and southwest, in contrast, heavy double arches and pier buttresses were erected to counter the thrust of the dome. The disparity of the type and strength of structural support provided by the these two supporting systems has in time caused the elliptical deformation of the dome base, whose diameter varies from 32.2 meters on the longitudinal axis to 32.7 meters along the transverse axis. Other factors, such as haste of original construction and uneven repair of vaulting through the centuries have multiplied the effects of the deformation, also visible on the piers and the grand arches. Flying buttresses were added to the northwest façade as early as the 9th or 10th century, supplemented by the construction of buttresses to the south and southeast by Andronicus II in early 13th century, amended by the Ottomans. These additions, among others, have transformed the exterior appearance of the church and the quality of light inside the nave and galleries.
The nave is paved with marble panels, which were revealed after the prayer rugs were removed in 1934. Its porphyry and verde antico columns, which were gathered from pagan temples of Western Anatolia, are crowned with elaborately carved capitals that bear the monogram of Justinian I. The decorative cornices separating the aisle, gallery and clerestory levels brace the structure and provide lateral support. There are no figural mosaics remaining of the original decoration of the church, which lasted well into the rule of Justinius II (565-578) after the completion of the structure. Of the mosaics set after the Iconoclastic era (726-842), some were lost to earthquakes, water damage and, most recently, tourists. The oldest mosaic in the church is found in the apse semi-dome and depicts the Virgin and the Child. Two angels are depicted on the semi-dome arch; the one on the right, mostly intact, is Archangel Gabriel. Above, to the left and right, mosaics of local saints lined up below clerestory windows and frescoes depicting Seraphim adorn the pendentives. A large amount of mosaics remains covered in the dome, whose roofing was recently renovated to prevent water damage during their conservation. Some of the most famous mosaics, including a Deisis panel and imperial portraits, are found in the southwest gallery, which was used for religious meetings and ceremonies.
There are many Ottoman additions visible in the nave, many of which were transformed during the Fossati restoration. Among earlier Ottoman work are two 16th century tile panels to the right of the mihrab, which depict the Holy Ka'aba and the other, shows the tomb of the Prophet. A band of blue tiles with Koranic inscriptions, signed 1607, wrap the sanctuary apsis below the window level. The marble minbar also believed to be of this period. There are four marble platforms abutting the piers; these and the muezzin's platform (müezzin mahfili) were built by Murad III in late 16th century. Murad IV (1612-1640) added the marble preacher's pulpit (kürsü), located next to the eastern niche. Working between 1847-49 under Abdülmecid II, The Fossati brothers rebuilt the mihrab and the sultan's lodge in the contemporary style and renovated the sultan's kiosk (hünkar köskü) to the north of the church, which provides access into the lodge from the exterior. Eight colossal disks, bearing the names of God, the Prophet, the four Caliphs and the two sons of Ali, were commissioned to calligrapher Kazasker Izzet Efendi and replaced older panels hanging on the piers. These works have been kept in place after secularization, while other calligraphic panels were taken to the Sultanahmet Mosque and the Museum of Turkish and Islamic Art. The wrought iron chandeliers and the stained glass windows in the sanctuary are also from the Fossati redecoration.
The Hagia Sophia has four minarets at its corners that were added at different times. The brick minaret at the southern corner is attributed to Mehmed II, and a second stone minaret was added to the north by Mimar Sinan during his restoration. The remaining two minarets are identical and date from the Murad III period.
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