Blue Mosque

The Sultan Ahmed Mosque (Turkish: Sultanahmet Camii) is the National mosque of Turkey in Istanbul, the largest city in Turkey and the capital of the Ottoman Empire (from 1453 to 1923). The mosque is one of several mosques known as the Blue Mosque for the blue tiles adorning the walls of its interior. It was built between 1609 and 1616, during the rule of Ahmed I. Like many other mosques, it also comprises a tomb of the founder, a madrasah and a hospice. The Sultan Ahmed Mosque has become one of the greatest tourist attractions of Istanbul.

History
After the humiliating Peace of Zsitvatorok and the unfavourable result of the wars with Persia, Sultan Ahmed I decided to build a large mosque in Istanbul to placate Allah. This would be the first imperial mosque in more than forty years. Whereas his predecessors had paid for their mosques with their war booty, Sultan Ahmed I had to withdraw the funds from the treasury, because he had not won any notable victories. This provoked the anger of the ulema, the Muslim legal scholars.

The mosque was to be built on the site of the palace of the Byzantine emperors, facing the Hagia Sophia (at that time the most venerated mosque in Istanbul) and the hippodrome, a site of great symbolic significance. Large parts of the southern side of the mosque rest on the foundations, the vaults and the undercrofts of the Great Palace. Several palaces, already built on the same spot, had to be bought (at considerable price) and pulled down, especially the palace of Sokollu Mehmet Pasa, and large parts of the Sphendone (curved tribune with U-shaped structure of the hippodrome).

Construction of the mosque started in August 1609 when the sultan himself came to break the first sod. It was his intention that this would become the first mosque of his empire. He appointed his royal architect Sedefhar Mehmet Aga, a pupil and senior assistant of the famous architect Sinan as the architect in charge of the construction. The organization of the work was described in meticulous detail in eight volumes, now in the library of the Topkapi Palace. The opening ceremonies were held in 1617 (although the gate of the mosque records 1616) and the sultan was able to pray in the royal box (hünkâr mahfil). But the building wasn't finished yet in this last year of his reign, as the last accounts were signed by his successor Mustafa I.

Architecture
The design of the Sultan Ahmed Mosque is the culmination of two centuries of Ottoman mosque development. It is the last great mosque of the classical period. The architect has ably synthesized the ideas of his master Sinan, aiming for overwhelming size, majesty and splendour, but the interior lacks his creative thinking.

Exterior
Mehmet Pasa used large quantities of materials for the construction, in particular stone and marble, draining away supplies for other important works. The layout of the mosque is irregular, as the architect had to take into account the existing constraints of the site. Its major façade, serving as the entrance, faces the hippodrome. The architect based his plan on the ?ehzade Mosque (1543-1548) in Istanbul, the first major large-scale work of Sinan, with the same square-based symmetrical quatrefoil plan and a spacious forecourt. This prayer hall is topped by an ascending system of domes and semi-domes, each supported by three exedrae, culminating in the huge encompassing central dome, which is 23.5 meters in diameter and 43 meters high at its central point. The domes are supported by four massive piers that recall those of the Selimiye Mosque in Edirne, another masterpiece of Sinan. It is obvious that Mehmet Pasa was overcautious by taking this inflated margin of safety, damaging the elegant proportions of the dome by their oppressive size. These "elephant feet" consist of multiple convex marble grooves at their base, while the upper half is painted, separated from the base by an inscriptive band with gilded words. Seen from the court, the profile of the mosque becomes a smooth succession of domes and semi-domes. The overall effect of the exterior on the visitor is one of perfect visual harmony, leading the eye up to the peak of the central dome.

The façade of the spacious forecourt was built in the same manner as the façade of the Süleymaniye Mosque, except for the addition of the turrets on the corner domes. The court is about as large as the mosque itself and is surrounded by a continuous, rather monotonous, vaulted arcade (revak). It has ablution facilities on both sides. The central hexagonal fountain is rather small in contrast with the dimensions of the courtyard. The monumental but narrow gateway to the courtyard stands out architecturally from the arcade. Its semi-dome has a fine stalactite structure, crowned by a rather small ribbed dome on a tall drum.

A heavy iron chain hangs in the upper part of the court entrance on the western side. Only the sultan was allowed to enter the court of the mosque on horseback. The chain was put there, so that the sultan had to lower his head every time he entered the court in order not to get hit. This was done as a symbolic gesture, to ensure the humility of the ruler in the face of the divine.

Interior
At its lower levels and at every pier, the interior of the mosque is lined with more than 20,000 handmade ceramic tiles, made at Iznik (the ancient Nicaea) in more than fifty different designs. The tiles at lower levels are traditional in design, while at gallery level their design becomes flamboyant with representations of flowers, fruit and cypresses. More than 20,000 tiles were made under the supervision of the Iznik master potter Kasici Hasan. However, the price the builders were able to pay for tiles was fixed by the sultan's decree, while tile prices increased over time. As a result, the tiles used later in building were of lesser quality. Their colours have faded and changed (red turning into brown and green into blue, mottled whites) and the glazes have dulled. The tiles on the back balcony wall are recycled tiles from the harem in the Topkapi Palace, when it was damaged by fire in 1574.

The upper levels of the interior are dominated by blue paint, but is of poor quality. More than 200 stained glass windows with intricate designs admit natural light, today assisted by chandeliers. On the chandeliers, ostrich eggs are found that were meant to avoid cobwebs inside the mosque by repelling spiders. The decorations include verses from the Qur'an, many of them made by Seyyid Kasim Gubari, regarded as the greatest calligrapher of his time. The floors are covered with carpets, which are donated by faithful people and are regularly replaced as they become worn out. The many spacious windows confer a spacious impression. The casements at floor level are decorated with opus sectile. Each exedra has five windows, some of which are blind. Each semi-dome has 14 windows and the central dome 28 (four of which are blind). The coloured glass for the windows was a gift of the Signoria of Venice to the sultan. Most of these coloured windows have by now been replaced by modern versions with little or no artistic merit.

The most important element in the interior of the mosque is the mihrab, which is made of finely carved and sculptured marble, with a stalactite niche and a double inscriptive panel above it. The adjacent walls are sheathed in ceramic tiles. But the many windows around it make it look less spectacular. To the right of the mihrab is the richly decorated minber, or pulpit, where the Imam stands when he is delivering his sermon at the time of noon prayer on Fridays or on holy days. The mosque has been designed so that even when it is at its most crowded, everyone in the mosque can see and hear the Imam.

The royal kiosk is situated at the south-east corner. It comprises a platform, a loggia and two small retiring rooms. It gives access to the royal loge in the south-east upper gallery of the mosque. These retiring rooms became the headquarters of the Grand Vizier during the suppression of the rebellious Janissary Corps in 1826. The royal loge (hünkâr mahfil) is supported by ten marble columns. It has its own mihrab, that used to be decorated with a jade rose and gilt and one hundred Qurans on inlaid and gilded lecterns.

The many lamps that light the interior was once covered with gold and gems . Among the glass bowls one could find ostrich eggs and crystal balls . All these decorations have been removed or pillaged for museums.

The great tablets on the walls are inscribed with the names of the caliphs and verses from the Quran, originally by the great 17th-century calligrapher Ametli Kasim Gubarim, but they have frequently been restored.

Minarets
The Sultan Ahmed Mosque is one of the two mosques in Turkey that has six minarets, the other is in Adana. When the number of minarets was revealed, the Sultan was criticized for presumption, since this was, at the time, the same number as at the mosque of the Ka'aba in Mecca. He overcame this problem by paying for a seventh minaret at the Mecca mosque.

Four minarets stand at the corners of the mosque. Each of these fluted, pencil-shaped minarets has three balconies (Serefe) with stalactite corbels, while the two others at the end of the forecourt only have two balconies.

Until recently the muezzin or prayer-caller had to climb a narrow spiral staircase five times a day to announce the call to prayer. Today a public address system is used, and the call can be heard across the old part of the city, echoed by other mosques in the vicinity. Large crowds of both Turks and tourists gather at sunset in the park facing the mosque to hear the call to evening prayers, as the sun sets and the mosque is brilliantly illuminated by coloured floodlights.

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St. Sophia

Hagia Sophia ("Holy Wisdom", Turkish: Ayasofya) is a former patriarchal basilica, later a mosque, now a museum, in Istanbul, Turkey. Famous in particular for its massive dome, it is considered the epitome of Byzantine architecture. It was the largest cathedral in the world for nearly a thousand years, until the completion of the Medieval Seville Cathedral in 1520.

The current building was originally constructed as a church between 532 and 537 AD on the orders of the Byzantine Emperor Justinian, and was in fact the third Church of the Holy Wisdom to occupy the site (the previous two had both been destroyed by riots). It was designed by two architects, Isidore of Miletus and Anthemius of Tralles. The Church contained a large collection of holy relics and featured, among other things, a 50 ft (15 m) silver iconostasis. It was the patriarchal church of the Patriarch of Constantinople and the religious focus point of the Eastern Orthodox Church for nearly 1000 years.

In 1453, Constantinople was conquered by the Ottoman Turks and Sultan Mehmed II ordered the building to be converted into a mosque. The bells, altar, iconostasis, and sacrificial vessels were removed, and many of the mosaics were eventually plastered over. The Islamic features - such as the mihrab, the minbar, and the four minarets outside - were added over the course of its history under the Ottomans. It remained as a mosque until 1935, when it was converted into a museum by the secular Republic of Turkey.

For almost 500 years the principal mosque of Istanbul, Hagia Sophia served as a model for many of the Ottoman mosques such as the Sultan Ahmed Mosque (Blue Mosque of Istanbul), the Sehzade Mosque, the Süleymaniye Mosque, and the Rüstem Pasha Mosque.

Although it is sometimes referred to as Saint Sophia (Greek for wisdom), the Greek name in full is Church of the Holy Wisdom of God ?a?? t?? ???a? t?? Te?? S?f?a? - and it was dedicated to the Holy Wisdom of God rather than a specific saint named Sophia.

As often happened in those days, the site was selected because there had been a pagan temple there. The church was built next to the area where the imperial palace was being developed and next to the smaller church Hagia Eirene, finished first and acting as cathedral until the Hagia Sophia was completed. The Hagia Sophia was inaugurated by Constantius II on 15 February 360. Both churches acted together as the principal churches of the Byzantine Empire.

This church was chronicled by Socrates of Constantinople (380-440), who claimed that it was built by Constantine the Great. It was built as a traditional Latin colonnaded basilica with galleries and a wooden roof. It was preceded by an atrium. This first church was then already claimed to be one of the world's most outstanding monuments.

The appellation "Megále Ekklesía" continued to be used for a long time, only to be replaced by the name "Hagia Sophia" after the conquest of Byzantium in 1453.

Second church
The patriarch of Constantinople, John Chrysostom, came into a conflict with Empress Aelia Eudoxia, wife of the Emperor Arcadius and was sent into exile on 20 June 404. During the subsequent riots, this first church was largely burned down. A second church was ordered by Theodosius II, who inaugurated it on 10 October 405. The fire that started during the tumult of the Nika Revolt resulted in the destruction of the (second) Hagia Sophia that burned down to the ground on 13-14 January 532. Several marble blocks of this second church have survived to our date, and are displayed in the garden of the current (third) church. These marble slabs were excavated in the western courtyard by A.M. Schneider in 1935. They were part of a monumental front entrance.

Third church
On 23 February 532, only a few days after the destruction of the second basilica, Emperor Justinian I took the decision to build a third and entirely different basilica, larger and more majestic than its predecessors.

Justinian chose the physicist Isidore of Miletus and the mathematician Anthemius of Tralles as architects; Anthemius, however, died within the first year. The construction is described by the Byzantine historian Procopius' On Buildings (De Aedificiis). The emperor had material brought over from all over the empire, such as Hellenistic columns from the temple of Artemis at Ephesus. Large stones were brought from far-away quarries: porphyry from Egypt, green marble from Thessaly, black stone from the Bosporus region and yellow stone from Syria. More than ten thousand people were employed during this construction. This new church was immediately recognized as a major work of architecture, demonstrating the creative insights of the architects. They may have used the theories of Heron of Alexandria to be able to construct a huge dome over such a large open space. The emperor, together with the patriarch Eutychius, inaugurated the new basilica on December 27, 537 with much pomp and circumstance. The mosaics inside the church were, however, only completed under the reign of Emperor Justin II (565-578).

Earthquakes in August 553 and on 14 December 557 caused cracks in the main dome and the eastern half-dome to appear. The main dome collapsed completely during an earthquake on 7 May 558, destroying the ambon, the altar and the ciborium over it. The emperor ordered an immediate restoration. He entrusted it to Isodorus the Younger, nephew of Isidore of Miletus. This time he used lighter materials and elevated the dome by 6.25 meters, thus giving the building its current interior height of 55.6 meters. [3]. This reconstruction, giving the church its present 6th century form, was completed in 562. The Byzantine poet Paul the Silentiary composed an extant, long epic poem, known as Ekphrasis, for the rededication of the basilica, presided over by Patriarch Eutychius, on 23 December 562.

Hagia Sophia was the seat of the Orthodox patriarch of Constantinople and a principal setting for Byzantine imperial ceremonies, such as crowning ceremonies. The basilica also offered asylum to wrongdoers. Foreign visitors were deeply impressed.

In 726 the Emperor Leo the Isaurian issued a series of edicts against the worship of images (iconoclasm), ordering the army to destroy all icons. At that time, all religious pictures and statues were removed from the Hagia Sophia. After a brief reprieve under Empress Irene (797-802), the iconoclasts made a comeback. Emperor Theophilus (829-842) was strongly influenced by the Islamic art, forbidding graven images. He had a two-winged bronze door with his monograms installed at the southern entrance of the church.

The basilica suffered damage, first by a great fire in 859, and again by an earthquake on 8 January 869 that made a half-dome collapse. Emperor Basil I ordered the church to be repaired.

After the great earthquake of 25 October 989, which ruined the great dome of Hagia Sophia, the Byzantine emperor Basil II asked for the Armenian architect Trdat, creator of the great churches of Ani and Agine, to repair the dome.[4]. His main repairs were to the western arch and a portion of the dome. The extent of the church's destruction meant that reconstruction lasted six years. The church was re-opened on 13 May 994.

In his book De Ceremoniis aulae Byzantinae (Book of Ceremonies), emperor Constantine VII (913-919) wrote about all the details of the ceremonies held in the Hagia Sophia by the emperor and the patriarch.

Tomb of Enrico Dandolo, the Doge of Venice who commanded the Sack of Constantinople in 1204, inside the Hagia SophiaAt the capture of Constantinople during the Fourth Crusade, the church was ransacked and desecrated. The Byzantine Greek historian Niketas Choniates described the capture of Constantinople. Many relics from the church, such as a stone from the tomb of Jesus, the Virgin Mary's milk, the shroud of Jesus, and bones of several saints, were sent to churches in the West and can be seen now in various museums in the West. During the Latin occupation of Constantinople (1204–1261) the church became a Roman Catholic cathedral. Baldwin I of Constantinople was crowned emperor on 16 May 1204 in the Hagia Sophia, at a ceremony which closely followed Byzantine practices. Enrico Dandolo, the Doge of Venice who commanded the sack and invasion of the city by the Latin Crusaders in 1204, is buried inside the church. The tomb inscription carrying his name, which has become a part of the floor decoration, was spat upon by many of the angry Byzantines who recaptured Constantinople in 1261. However, restoration carried out during the period 1847-1849 cast doubt upon the authenticity of the doge's grave. It is more likely a symbolic burial site to keep alive his memory.

After the recapture in 1261 by the Byzantines, the church was in a dilapidated state. The four buttresses in the west were probably built during this time. In 1317, emperor Andronicus II ordered four new buttresses to be built in the eastern and northern parts of the church. After new cracks had developed in the dome after the earthquake of October 1344, several parts of the building collapsed on 19 May 1346. After that, the church remained closed until 1354, when repairs were undertaken by the architects Astras and Peralta.

Mosque
Immediately after the Ottoman Turks conquered Constantinople (Istanbul) in 1453, the Hagia Sophia was converted to a mosque. At that time, the church was very dilapidated. Several of its doors had fallen off. This condition was described by several Western visitors, such as the Córdoban nobleman Pero Tafur[5] and the Florentine Cristoforo Buondelmonti.[6] The sultan Mehmed II ordered the immediate cleanup of the church and its conversion to a mosque. The next sultan Bayezid II built a new minaret, replacing the one built by his father.

In the 16th century the sultan Suleiman the Magnificent (1520-1566) brought back two colossal candles from his conquest of Hungary.

They were placed on both sides of the mihrab. During the reign of Selim II (1566-1577), the building started showing signs of fatigue and was extensively strengthened with the addition of structural supports to its exterior by the great Ottoman architect Sinan, who is also considered one of the world's first earthquake engineers. In addition to strengthening the historic Byzantine structure, Sinan built the two additional large minarets at the western end of the building, the original sultan's loge, and the mausoleum of Selim II to the southeast of the building (then a mosque) in 1577. The mausoleums of Murad III and Mehmed III were built next to it in the 1600s.

Later additions were the sultan's gallery, a minbar decorated with marble, a dais for a sermon and a loggia for a muezzin.

The sultan Murad III (1574-1595) had two large alabaster Hellenistic urns transported from Pergamon and placed on two sides of the nave.

Sultan Mahmud I ordered the restoration of the building in 1739 and added a medrese (a Koranic school, now the library of the museum), a soup kitchen (for distribution to the poor) and a library, and in 1740 a fountain for ritual ablutions (Sadirvan), thus transforming it into a külliye, i.e. a social complex. At the same time a new sultan's gallery and a new mihrab were built inside.

View of one of the wooden disks inside the Ayasofya from the first floorThe most famous restoration of the Hagia Sophia was ordered by Sultan Abdülmecid and completed by eight hundred workers between 1847 and 1849, under the supervision of the Swiss-Italian architect brothers Gaspare and Giuseppe Fossati. The brothers consolidated the dome and vaults, straightened the columns, and revised the decoration of the exterior and the interior of the building. The mosaics in the upper gallery were cleaned. The old chandeliers were replaced by new pendant ones. New gigantic circular-framed disks were hung on columns. They were inscribed with the names of Allah, the prophet Muhammad, the first four caliphs Abu Bakr, Umar, Uthman and Ali, and the two grandchildren of Mohammed: Hassan and Hussain, by the calligrapher Kazasker Izzed Effendi (1801-1877). In 1850 the architect Fossati built a new sultan's gallery in a Neo-Byzantine style connected to the royal pavilion behind the mosque. Outside the Hagia Sophia, a timekeeper's building and a new medrese were built. The minarets were altered so that they were of equal height. When the restoration was finished, the mosque was re-opened with ceremonial pomp on 13 July 1849.

Museum
In 1935, the first Turkish President and founder of the Republic of Turkey, Mustafa Kemal Atatürk, transformed the building into a museum. The carpets were removed and the marble floor decorations appeared for the first time in centuries, while the white plaster covering the mosaics was painstakingly removed by expert restorers.

Architecture
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 proclaimed, "Solomon, I have surpassed thee!" . 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 in Spain.

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. Under Justinian's orders, eight Corinthian columns were disassembled from Baalbek, Lebanon and shipped to Constantinople for the construction of Hagia Sophia.

The vast interior has a complex structure. The vast nave is covered by a central dome which has a maximum diameter of 31.24 meters and a height from floor level of 55.6 meters, about one fourth smaller than the dome of the Pantheon. The dome seems rendered weightless by the unbroken arcade of 40 arched windows under it, which help flood the colourful interior with light. Due to consecutive repairs in the course of its history, the dome has lost its perfect circular base and has become somewhat elliptical with a diameter varying between 31.24 and 30.86 m.

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. These were reinforced with buttresses during Ottoman times, under the guidance of the architect Sinan.

At the western (entrance) and eastern (liturgical) ends, the arched openings are extended by half domes carried on smaller semi-domed 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. Despite all these measures, the weight of the dome remained a problem, which was solved by adding buttresses from the outside.

Marble jar from PergamonAll interior surfaces are sheathed with polychrome marbles, green and white with purple porphyry and gold mosaics, encrusted upon the brick. This sheathing camouflaged the large pillars, giving them, at the same time, a brighter aspect.

On the exterior, simple stuccoed walls reveal the clarity of massed vaults and domes. The yellow and red colour of the exterior was added by the architect Fossati during the restorations in the 19th century.

Marble jar
The marble jar was brought from Pergamon during the reign of Sultan Murad III. Originally from the Hellenistic period, it was carved from a single block of marble.

Imperial Gate
The Imperial Gate was the main entrance between the exo- and esonarthex. It was reserved only for the emperor. The Byzantine mosaic above the portal depicts Christ and Emperor Leo VI the Wise.

Minarets
One of the minarets (at southwest) was built from red brick while the other three were built from white marble; of which the slender one at northeast was erected by Sultan Bayezid II while the two larger minarets at west were erected by Sultan Selim II and designed by the famous Ottoman architect Sinan. The reason for the varying dimensions and mass of the minarets was to counterweight the main structure's mass and distribute the weight uniformly. This application by Mimar Sinan was one of the earliest seismic and geotechnical engineering efforts in the world. Latest research shows that without the counterweight of the minarets, the main structure would tend to collapse.

Dome
The dome of 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 Hagia Sophia weakened the overall structure. The bricklayers used more mortar than brick, which weakened the walls. The structure would have been more stable if the builders at least let the mortar cure 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. Isidore 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. 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 Hagia Sophia show how this structure is one of the most advanced and ambitious monuments of late antiquity.

Upper Imperial Gallery
Loge of the Empress
The Loge of the Empress is located in the centre of the upper enclosure, or gallery, of the Hagia Sophia. From there the empress and the court-ladies would watch the proceedings down below. A round, green stone marks the spot where the throne of the empress stood.

Marble Door
The Marble Door inside the Hagia Sophia is located in the southern upper enclosure, or gallery. It was used by the participants in synods, they entered and left the meeting chamber through this door.

Decorations
Originally, under Justinian's reign, the interior decorations consisted of abstract designs of the marble slabs on the walls and mosaics on the curving vaults. Of these, one can still see the two archangels Gabriel and Michael in the spandrels of the bema. There were already a few figurative decorations, as attested by the eulogy of Paul the Silentiary. The spandrels of the gallery are revetted in opus sectile, showing patterns and figures of flowers and birds in precisely cut pieces of white marble set against a background of black marble. In later stages figurative mosaics were added, which were destroyed during the iconoclastic controversy (726-843). Present mosaics are from the post-iconoclastic period. The number of treasures, relics and miracle-working, painted icons of the Hagia Sophia grew progressively richer into an amazing collection. Apart from the mosaics, a large number of figurative decorations were added during the second half of the ninth century: an image of Christ in the central dome; Orthodox saints, prophets and Church Fathers in the tympana below; historical figures connected with this church, such as Patriarch Ignatius; some scenes from the gospel in the galleries.

Mosaics
The church was richly decorated with mosaics throughout the centuries. They either depicted the Virgin Mother, Jesus, Saints, or emperors and empresses. Other parts were decorated in a purely decorative style with geometric patters.

During the Sack of Constantinople in 1204, the Latin Crusaders vandalized the valuable items in every important Byzantine structure of the city, including the golden mosaics of the Hagia Sophia. Much of these valuable items were shipped to Venice, whose Doge, Enrico Dandolo, had organized the invasion and sack of Constantinople.

Following the building's conversion into a mosque in 1453, many of its mosaics were destroyed or covered with plaster, due to Islam's ban on representational imagery. This process was not completed at once, and reports exist from the 17th century in which travellers note that they could still see Christian images in the former church. In 1847-49, the building was restored by two Swiss brothers, Gaspare and Giuseppe Fossati, and Sultan Abdülmecid allowed them to also document any mosaics they might discover during this process. This work did not include repairing the mosaics and after recording the details about an image, the Fossatis painted it over again. This work included covering the previously uncovered faces of two seraphim mosaics located in the centre of the building. The building currently features a total of four of these images and two of them are restorations in paint created by the Fossatis to replace two images of which they could find no surviving remains. In other cases, the Fossatis recreated damaged decorative mosaic patterns in paint, sometimes redesigning them in the process. The Fossati records are the primary sources about a number of mosaic images now believed to have been completely or partially destroyed in an earthquake in 1894. These include a great mosaic of Christ Pantocrator in the dome, a mosaic over a now unidentified Door of the Poor, a large image of a jewel-encrusted cross and a large number of images of angels, saints, patriarchs, and church fathers. Most of the missing images were located in the building's two tympana. The Fossatis also added a pulpit (minbar) and the four large medallions on the walls of the nave bearing the names of Muhammad and Islam's first caliphs.

Imperial Gate mosaic
Imperial Gate mosaics: located in the tympanum above the gate used only by the emperors when entering the church. Based on style analysis, it has been dated to the late 9th or early 10th century. It represents the emperor Leo VI bowing down before Christ Pantocrator, giving His blessing and holding in His left hand an open book. The text on the book reads as follows : "Peace be with you. I am the light of the world". On each side of Christ's shoulders is a circular medallion : on His left the Archangel Gabriel (founder of the church), on His right His Mother Mary. These mosaics express the timeless power bestowed by Christ on the Byzantine emperors.

Southwestern entrance mosaic
Southwestern entrance mosaics, situated in the tympanum of the southwestern entrance, date from 944. They were rediscovered during the restorations of 1849 by Fossati. The Virgin sits on a throne without a back, her feet resting on a pedestal, embellished with precious stones. The Child Christ sits on her lap, giving His blessing and holding a scroll in His left hand. On her left side stands emperor Constantine in ceremonial attire, presenting a model of the city to Mary. The inscription next to him says : "Great emperor Constantine om the Saints". On her right side stands emperor Justinian I, offering a model of the Hagia Sophia. The medallions on both sides of the Virgin's head carry the monograms MP and OY, an abbreviation of "Mater" and "Theou", meaning "Mother of God".

Apse mosaics
Virgin and Child: this was the first of the post-iconoclastic mosaics. It was inaugurated on 29 March 867 by Patriarch Photios and the emperors Michael III and Basil I. This mosaic is situated in a high location on the half dome of the apse. Mary is sitting on a throne without a back, holding the Child Jesus on her lap. Her feet rest on a pedestal. Both the pedestal and the throne are adorned with precious stones. These mosaics are a reconstruction of the mosaics of the sixth century that were previously partly destroyed. The mosaics are set against the original golden background of the 6th century. The portraits of the archangels Gabriel and Michael (largely destroyed) in the bema of the arch also date from the 9th century.

Upper Gallery
Several mosaics are preserved in the upper gallery, an area traditionally reserved for the empress and her court. The best-preserved mosaics are located in the southern part of the gallery.

Emperor Alexander mosaic
The Emperor Alexander mosaic is not easy to find for the first-time visitor, located in the upper parts close to the ceiling. It depicts Emperor Alexander in full regalia, holding a skull in his left hand.

Empress Zoe mosaics
The Empress Zoe mosaics on the eastern wall of the southern gallery date from the 11th century. Christ Pantocrator, clad in the dark blue robe (as always the custom in Byzantine art), is seated in the middle against a golden background, giving His blessing with the right hand and holding the Bible in His left hand. On either side of His head are the monograms IC and XC, meaning "Iessus Christos". He is flanked by Constantine IX Monomachos and Empress Zoe, both in ceremonial costumes. He is offering a purse, as symbol of the donation he made to the church, while she is holding a scroll, symbol of the donations she made. The inscription over the head of the emperor says : "Constantine Monomachos, the pious ruler of Romans and the servant of God's Jesus". The inscription over the head of the empress reads as follows : "Very pious Augusta Zoë". The previous heads have been scraped off and replaced by the three present ones. Perhaps the earlier mosaic showed her first husband Romanos III Argyros or her adopted son Michael IV. Another theory is that these mosaics were made for an earlier emperor and empress, with their heads changed into the present ones.

Comnenos mosaic
The Mosaics of the Comnenos, equally located on the eastern wall of the southern gallery, date from 1122. The Virgin Mary is standing in the middle, depicted, as usual in Byzantine art, in a dark blue gown. She holds the Child Christ on her lap. He gives His blessing with His right hand while holding a scroll in His left hand. On her right side stands emperor John II Komnenos, represented in a garb embellished with precious stones. He holds a purse, symbol of an imperial donation to the church. Empress Eirene stands on the left side of the Virgin, wearing ceremonial garments, offering a document. Their eldest son Alexius Comnenos is represented on an adjacent pilaster. His mournful features, reflect his death from tuberculosis in the same year. In this panel one can already see a difference with the Empress Zoe mosaics that is one century older. There is a more realistic expression in the portraits instead of an idealized representation. The empress is shown with plaited blond hair, rosy cheeks and grey eyes, revealing her Hungarian descent. The emperor is depicted in a dignified manner.

Deësis mosaic
The Deësis (Entreaty) mosaic probably dates from 1261. It was commissioned to mark the end of 57 years of Roman Catholic use and the return to the Orthodox faith. It is the third panel situated in the imperial enclosure of the upper galleries. It is widely considered the finest in Hagia Sophia, because of the softness of the features, the humane expressions and the tones of the mosaic. The style is close to that of the Italian painters of the late 13th or early 14th century, such as Duccio. In this panel the Virgin Mary and John the Baptist (Ioannes Prodromos), both shown in three-quarters profile, are imploring the intercession of Christ Pantocrator for humanity on Judgment Day. The bottom part of this mosaic is badly deteriorated, probably due to rain since the mosaic is next to the windows. This mosaic is considered as the beginning of the Renaissance in Byzantine pictorial art.

Northern tympanon mosaics
The northern tympanon mosaics feature various saints. They have been able to survive due to the very high and unreachable location. They depict Saints John Chrysostom and Ignatius the Younger standing, clothed in white robes with crosses, and holding richly jewelled Holy Bibles. The names of each saint is given around the statues in Greek, in order to enable an identification for the visitor. The other mosaics in the other tympani have not survived probably due to the frequent earthquakes as opposed to any deliberate destruction by the Ottoman conquerors.

20th-century restoration
A large number of mosaics were uncovered in the 1930s by a team from the American Byzantine Institute led by Thomas Whittemore. The team chose to let a number of simple cross images remain covered by plaster, but uncovered all major mosaics found.

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 would have to 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).