The Church of the Holy Wisdom, commonly known as Hagia Sophia in English, is a former Eastern Orthodox church converted to a mosque, now converted into a museum, in Istanbul (Constantinople). It is universally acknowledged as one of the greatest buildings of the world and sometimes considered the Eighth Wonder of the World.

The name comes from the Greek name ???a S?f?a. It is also known as Sancta Sophia in Latin and Ayasofya in Turkish.

Construction

Nothing remains of the first church that was built on the same site during the 4th century. Following the destruction of the first church, a second was built by Constantius, the son of Constantine the Great, but was burned down during the Nika riots of 532. The building was rebuilt under the personal supervision of emperor Justinian I and rededicated on December 27, 537.

Justinian chose Isidore of Miletus and Anthemius of Tralles, a physicist and a mathematician, as architects; Anthemius, however, died within the first year. The construction is described in Procopius' On Buildings (De Aedificiis). The Byzantine poet Paulus the Silentiary composed an extant poetic ekphrasis, probably for the rededication of 563, which followed the collapse of the main dome.

Hagia Sophia is one of the greatest surviving examples of Byzantine architecture. Of great artistic value was its decorated interior with mosaics and marble pillars and coverings. The temple itself was so richly and artistically decorated that Justinian is said to have proclaimed 'Solomon, I have surpassed thee! (?e?????? se S???µ??)'. Justinian himself had overseen the completion of the greatest cathedral ever built up to that time, and it was to remain the largest cathedral for 1,000 years up until the completion of the cathedral in Seville. It is today the fourth largest cathedral in the world (by size, not height)

Justinian's basilica was at once the culminating architectural achievement of late antiquity and the first masterpiece of Byzantine architecture. Its influence, both architecturally and liturgically, was widespread and enduring in the Eastern Orthodox, Roman Catholic, and Muslim worlds alike.

The dome of the Hagia Sophia has spurred particular interest for many art historians and architects because of the innovative way the original architects envisioned the dome. The dome is supported by pendentives which had never been used before the building of this structure. The pendentive enables the round dome to transition gracefully into the square shape of the piers below. The pendentives not only achieve a pleasing aesthetic quality, but they also restrain the lateral forces of the dome and allow the weight of the dome to flow downward. Although this design stabilizes the dome and the surrounding walls and arches, the actual construction of the walls of the Hagia Sophia weakened the overall structure. The bricklayers used more mortar than brick, which, of course, constitutes a weak wall. The structure would have been more stable had the builders at least let the mortar dry before they began the next layer, however, they did not do this. When the dome was placed atop the building, the weight of the dome caused the walls to lean outward because of the wet mortar underneath. When Isidorus the Younger rebuilt the original dome, he had to first build up the interior of the walls so that they were vertical in order to support the weight of the new dome. Another probable change in the design of the dome when it was rebuilt was the actual height of the dome. Isidorus the Younger raised the height of the dome by approximately twenty feet so that the lateral forces would not be as strong and the weight of the dome would flow more easily down the walls.

A second interesting fact about the original structure of the dome was how the architects were able to place forty windows around the base of the dome. The Hagia Sophia is famous for the mystical quality of light that reflects everywhere in the interior of the nave, which gives the dome the appearance of hovering above the nave. This design is possible because the dome is shaped like a scalloped shell or the inside of an umbrella with ribs that extend from the top of the dome down to the base. These ribs allow the weight of the dome to flow between the windows, down the pendentives, and ultimately to the foundation.

The anomalies in the design of the Hagia Sophia show how this structure is one of the most advanced and ambitious monuments since the fall of Rome.

Ottoman restorations and revisions

Many restorations and repairs were done by Ottoman architects. The most famous and most extensive work was done by the great Mimar Sinan in the 16th century: The dome of the Hagia Sophia was taken down, and a new dome was constructed, the old minarets were also demolished, the minarets were added which can be seen today, as well as Islamic pulpits and art.

In the following 400 years, after each successive big earthquake and largescale city fire, new repairs and renovations of the Hagia Sophia took place, to conserve it until today.

Description

Hagia Sophia is covered by a central dome with a diameter of 31 meters (102 feet) and 56 metres high, slightly smaller than the Pantheon's. The dome seems rendered weightless by the unbroken arcade of arched windows under it, which help flood the colourful interior with light. The dome is carried on pendentives—four concave triangular sections of masonry which solve the problem of setting the circular base of a dome on a rectangular base. At Hagia Sophia the weight of the dome passes through the pendentives to four massive piers at the corners. Between them the dome seems to float upon four great arches.

At the western (entrance) and eastern (liturgical) ends, the arched openings are extended by half domes carried on smaller semidomed exedras. Thus a hierarchy of dome-headed elements builds up to create a vast oblong interior crowned by the main dome, a sequence unexampled in antiquity.

The structure has been severely damaged several times by earthquakes. The dome collapsed after an earthquake in 558; its replacement fell in 563. There were additional partial collapses in 989 and 1346. In the era of Süleyman the Magnificent, Mimar Sinan (Sinan the Architect) built extra attachments to prevent it from collapsing.

All interior surfaces are sheathed with polychrome marbles, green and white with purple porphyry and gold mosaics, encrusted upon the brick. On the exterior, simple stuccoed walls reveal the clarity of massed vaults and domes.

Later History

Hagia Sophia was the seat of the Orthodox patriarch of Constantinople and a principal setting for imperial ceremonies. During the Latin Occupation (1204-1261) the church became a Roman Catholic cathedral, and its many treasures and relics were dispersed. It was converted to a mosque after the Fall of Constantinople to the Ottoman Turks under Sultan Mehmed II in 1453. Since more conservative factions of Islam consider the depiction of the human form to be blasphemous, its mosaics were covered with plaster. One must note, however, that due to the foresightedness and tolerance of the Ottoman Sultans, the plaster was periodically removed,the mosaics maintained, and replastered. For almost 500 years the principal mosque of Istanbul, Ayasofya served as model for many of the Ottoman mosques such as the Shehzade Mosque, the Suleiman Mosque, and the Rüstem Pasha Mosque. The 19th century restoration of the Fossati brothers, who also built a pulpit (minbar) and the four circular medallions hanging on the walls of the nave that bear the names of Muhammad and the first caliphs, is widely deemed to have destroyed much of the original mosaics.

Restoration work in the 20th century began in 1932 by the American Byzantine Institute, when most of the figures were uncovered. In 1934, under Turkish president Kemal Atatürk, Hagia Sophia was secularized and turned into the Ayasofya Museum.

Due to its long history as both a church and a mosque, a particular challenge arises in the restoration process. The Christian iconographic mosaics are being gradually uncovered. However, in order to do so, important, historic Islamic art must be destroyed. Restorers have attempted to maintain a balance between both Christian and Islamic cultures. In particular much controversy rests upon whether the Islamic calligraphy on the dome of the cathedral should be removed, in order to permit the underlying Pantocrator mosaic of Christ as Master of the World, to be exhibited (assuming the mosaic still exists).

However, work has reportedly been purposely slow on the Hagia Sophia due to its important position and symbolism within the Eastern Orthodox Church. The Ecumenical Patriarch of the Greek Orthodox Church has claimed that the Turkish Government has denied offers to provide monetary assistance for the further restoration of Hagia Sophia in order to downplay its importance. Some Orthodox and Catholic Christians have gone so far as to demand the return of Hagia Sophia to the Orthodox Christian religion as a condition of Turkey's entry into the European Union.

In 2002 Reuters reported that many mosaics and icons stored in the basement of the cathedral had been damaged by damp, giving rise to questions as to whether the Turkish authoriries were best placed to preserve the monument. It was further pointed out in 2005 that the scaffolding beneath the dome of the cathedral had been placed there since 1995 without restoration of the dome being completed, again giving rise to questions as to whether such restoration work was genuine.