Hagia Sophia: Byzantine Basilica and Imperial Mosque in Istanbul
Site at a Glance
- Rating
- 4.8
- Popularity
- Very High
- Country
- Turkey
- Primary era
- Medieval
- External website
- Open
- Eras represented
- Classical, Medieval, Early Modern
- Civilizations
- Byzantine, Ottoman, Roman
- Site type
- Religious
- Remains
- Cathedral
On this page22 sections
History
Hagia Sophia is a Byzantine basilica in Sultan Ahmet, Istanbul, Türkiye, built in its present form between 532 and 537 during the reign of Emperor Justinian I. It occupies the site of three successive churches and became the cathedral of Constantinople, the seat of the Ecumenical Patriarch, and a principal setting for Byzantine imperial ceremonies.
The first and second churches
The first church, known as the Magna Ecclesia or Great Church, was consecrated on 15 February 360 during the reign of Constantius II by Eudoxius of Antioch. Its foundation was traditionally attributed to Constantine the Great, but the chronology makes construction under Constantius II more probable. The building probably had a timber roof, columns, curtains, a western entrance, and a narthex, or church entrance hall. An atrium may have stood before it, although its precise plan remains uncertain. It may have been a U-shaped basilica or a conventional basilica with several aisles.
A treasury for liturgical objects, known as a skeuophylakion, may initially have served a funerary purpose. Much of the first church was burned during riots following the exile of Patriarch John Chrysostom on 20 June 404. The main basilica may have been destroyed while some associated buildings survived.
Emperor Theodosius II ordered a replacement church, designed by the architect Rufinus and inaugurated on 10 October 415. It formed part of a larger walled complex shared with Hagia Irene and served as the Great Church of Constantinople. The building was burned on 13 and 14 January 532 during the Nika Revolt, a major uprising against Justinian I that caused extensive destruction in the capital.
Justinian’s basilica
Justinian began the present church on 23 February 532, only weeks after the destruction of the Theodosian basilica. He commissioned Anthemius of Tralles and Isidore of Miletus to create a building that would surpass its predecessors in scale and magnificence. More than 10,000 workers took part in construction, while materials arrived from across the Mediterranean. Justinian and Patriarch Menas inaugurated the basilica on 27 December 537. Some of its mosaics were completed during the reign of Justin II.
Hagia Sophia became the patriarchal cathedral of Constantinople and the main church associated with the Byzantine imperial court. It hosted coronations and other state ceremonies, and it could provide sanctuary to people facing persecution. The limits of this protection, particularly for those accused of murder, were disputed.
Earthquakes in 553 and 557 damaged the building. In 558, the eastern semidome collapsed, destroying the ambon, altar, and ciborium. Justinian entrusted Isidore the Younger with rebuilding the vault using lighter materials and raising it to a greater height. Completed in 562, this work gave Hagia Sophia its essential sixth-century form.
Later Byzantine changes and damage
During the Byzantine-Sasanian War of 602 to 628, some liturgical vessels may have been melted down during the reign of Heraclius. In 623, the relic of the Virgin Mary’s garment was temporarily brought from Blachernae to Hagia Sophia during the Avar threat to Constantinople. The church also became a place of political protest and diplomatic activity during the siege of 626.
Imperial iconoclasm, the Byzantine controversy over the use and veneration of religious images, led to the removal of images and statues in the eighth and early ninth centuries. After the restoration of image veneration, new mosaics depicting Christ, the Virgin Mary, angels, prophets, and church fathers were installed.
A major fire damaged the basilica in 859, and an earthquake in 869 brought down a semidome. Basil I ordered repairs. Another earthquake in 989 destroyed the western dome arch, after which Basil II commissioned the Armenian architect Trdat to direct a six-year repair and rebuilding campaign. Hagia Sophia reopened on 13 May 994.
In 1054, the papal envoy Humbert of Silva Candida formally delivered the excommunication of Patriarch Michael I Cerularius inside Hagia Sophia. The event is traditionally associated with the beginning of the East-West Schism between the Roman Catholic and Eastern Orthodox churches.
Crusader occupation and Byzantine restoration
During the Fourth Crusade, western European and Venetian forces captured Constantinople in 1204. Hagia Sophia was looted and desecrated and became the cathedral of the Latin Empire, the Crusader state established in Constantinople between 1204 and 1261. Baldwin I was crowned emperor there on 16 May 1204, and the Venetian doge Enrico Dandolo was buried in the church.
After the Byzantine reconquest of Constantinople in 1261, Hagia Sophia returned to Orthodox use but remained in deteriorated condition. Andronicus II ordered four new buttresses in 1317. Earthquakes in 1344 and 1346 caused further cracking and collapses, and repairs began in 1354 under the architects Astras and Peralta.
Ottoman mosque
Ottoman forces captured Constantinople on 29 May 1453. Sultan Mehmed II immediately ordered Hagia Sophia to be converted into a mosque, and the first Friday prayer took place there on 1 June. It became the first imperial mosque of Istanbul and remained the city’s principal mosque until the construction of the Sultan Ahmed Mosque in 1616.
Christian furnishings and imagery were removed or concealed, while the building received a mihrab, a niche indicating the direction of Mecca, a minbar, or raised pulpit for the Friday sermon, and minarets. Many mosaics were covered with plaster. The mosque and its surrounding properties were supported by a waqf, a legally endowed charitable foundation whose revenues supported the religious complex and related public functions.
A small minaret had been added by 1481, and Bayezid II commissioned another at the northeast corner. One collapsed during the earthquake of 1509, and the early minarets were replaced in the sixteenth century. Selim II later commissioned two additional western minarets and extensive structural strengthening from the architect Mimar Sinan.
Sinan added external buttresses and two minarets, built the mausoleum of Selim II in 1576 and 1577, and cleared houses within a surrounding protected zone. Later Ottoman rulers added dynastic mausoleums and converted the baptistery into the tomb of Mustafa I. A campaign ordered by Mahmud I in 1739 and 1740 added a madrasa, library, soup kitchen, fountain for ritual ablutions, and a new mihrab, turning Hagia Sophia into a mosque complex.
The renewal of the interior plaster in 1717 helped preserve many mosaics. Sultan Abdulmejid I commissioned a major restoration between 1847 and 1849 under the Swiss-Italian architects Gaspare and Giuseppe Fossati. The work consolidated the dome and vaults, straightened columns, revised the interior and exterior decoration, exposed and cleaned upper-gallery mosaics, and repaired the minarets and mosque furnishings.
Museum and renewed mosque
In 1935, Mustafa Kemal Atatürk converted Hagia Sophia into a museum in the secular Republic of Turkey. Carpets and mortar were removed, revealing marble floor decoration including the omphalion, while many mosaics were uncovered. Conservation campaigns from 1997 to 2006 addressed the leaking roof, structural instability, dome damage, moisture, and mosaic preservation. The work included roof stabilization, dome repairs, and training for Turkish conservators.
Hagia Sophia was inscribed in 1985 as part of the UNESCO World Heritage property Historic Areas of Istanbul. Turkey’s Council of State annulled its museum status on 10 July 2020, after which the building was redesignated as a mosque. The first Friday prayers following the conversion took place on 24 July 2020. The decision drew criticism from UNESCO, the World Council of Churches, the International Association of Byzantine Studies, the Turkish opposition, and international governments and religious leaders. UNESCO subsequently requested information about the building’s conservation and management.
An extensive restoration and preservation program began in 2025. Its work includes investigating the lead covering of the dome, strengthening the connections between the dome and semidomes, examining supporting pillars and subterranean structures, and improving resistance to earthquakes.
Remains
The surviving complex combines the sixth-century basilica with earlier archaeological remains, Byzantine repairs, Ottoman additions, and later conservation work. The present building is approximately 82 metres long and 73 metres wide, with a maximum interior height of about 55.6 metres. Its rectangular plan contains a central nave, side aisles, galleries, a western entrance sequence, and an eastern liturgical zone.
The central basilica
Dome and vaults
The central dome rises from four massive piers and pendentives, curved triangular structures that transform a square space into a circular support for a dome. It measures approximately 32.7 to 33.5 metres in diameter, although later repairs left it somewhat elliptical, with measured diameters of about 31.24 and 30.86 metres. Forty arched windows encircle its lower edge, forming a bright band between the dome and its supports.
Large semidomes extend the interior to the east and west, while smaller semidomed exedrae create a sequence of curved spaces. The present dome and vaults preserve the rebuilding directed by Isidore the Younger after the collapse of 558. The reconstructed dome was raised about 6.25 metres above its predecessor and given a ribbed, pendentive-supported form. Eight Corinthian columns from Baalbek were transported to Constantinople around 560 for this rebuilding.
Construction and interior surfaces
Hagia Sophia is built chiefly of brick and mortar. Its unusually broad mortar joints contain sand and finely crushed ceramic material, while iron cramps and ties reinforce the structure. The original exterior had extensive marble revetment. Inside, polychrome marble, green and white stone, purple porphyry, and gold mosaics formed the principal materials and finishes.
The floor is predominantly Proconnesian marble, with bands of Thessalian green marble. A second Justinianic floor was laid over rubble after the first dome collapsed, and different stones marked important liturgical locations. During the mosque period, the floor was concealed beneath a carpet. The central nave, eastern sanctuary, western narthexes, galleries, and semidomes remain organized as a unified oblong interior.
Entrances and galleries
The western entrance sequence consists of the exonarthex, or outer entrance hall, the esonarthex, or inner entrance hall, and the Imperial Gate. Reserved for the emperor, the Imperial Gate connects the outer and inner narthexes. A long ramp from the northern part of the outer narthex leads toward the upper gallery.
The upper gallery includes the former imperial viewing area, where the empress and her court could observe ceremonies below. Its southern section contains the Marble Door, which was used by members of the synod and opens toward a chamber associated with patriarchal ceremonies and decision-making. Carved fruit and fish motifs decorate its surface. Graffiti in the galleries includes runic inscriptions probably associated with Varangian guards, elite imperial soldiers recruited from Scandinavian and later Rus’ communities.
Earlier archaeological remains
The Theodosian church
The Theodosian church occupied the area west of the present basilica. Its remains include foundations, columns, sculptural fragments, a western entrance, parts of an atrium, and fragments of a frieze showing twelve lambs representing the twelve apostles. Some excavation trenches remain visible near the western entrance.
The complex included a monumental propylaeum, or ceremonial entrance structure, a portico, an atrium, a steep western staircase, and a cistern that may have supplied a fountain or enabled ritual washing. The basilica had a western main entrance, a possible eastern entrance, a central pulpit, an upper gallery, polychrome floor mosaics, and carved decoration on its exterior.
The skeuophylakion
The fifth-century skeuophylakion is a rotunda whose lower two levels use banded masonry and whose third level is built of plain brick. Storage niches, an internal gallery reached by an external spiral staircase, marble-framed windows, and carved acanthus consoles survive as part of its architectural arrangement. Its foundations were cleared archaeologically in 1979, and the building was restored in 2014.
Byzantine decoration
Mosaics of Christ, Mary, and the emperors
The Imperial Gate mosaic, probably from the ninth or tenth century, shows Christ enthroned while an emperor and his son kneel before him. Medallions of the Virgin Mary and the archangel Gabriel flank Christ. In the southwestern vestibule, another mosaic depicts the Virgin and Child between Constantine, who presents a model of Constantinople, and Justinian I, who presents Hagia Sophia.
The apse mosaic of the Virgin and Child was inaugurated in 867 after the restoration of image veneration. The Virgin sits enthroned with the infant Christ, while damaged or largely lost images of the archangels Gabriel and Michael occupy the adjoining arch. In the upper gallery, the mosaic of Emperor Alexander shows him holding a scroll and a globus cruciger. The image was rediscovered in 1958 after being concealed beneath paint.
The eleventh-century Empress Zoe mosaic shows Christ enthroned between Constantine IX Monomachos and Empress Zoe. The emperor holds a purse representing a donation to the church, while Zoe holds a scroll representing her donations. The Comnenus mosaic, dated to 1122, shows the Virgin and Child between Emperor John II Komnenos and Empress Irene, with their son Alexios on a nearby pier.
The Deesis mosaic, probably dating from 1261, shows Christ between the Virgin Mary and John the Baptist. It marked the return of Hagia Sophia to Orthodox control after the Latin occupation and is substantially damaged. Other surviving decoration includes images of patriarchs, saints, prophets, church fathers, cherubim, geometric patterns, floral motifs, birds, and Gospel scenes.
Concealed and restored imagery
Many figurative mosaics were covered with plaster during the Ottoman period and later exposed, cleaned, or restored. The Fossati restoration documented numerous mosaics before covering them again. Later investigations by the Byzantine Institute and infrared studies identified concealed mosaics and examined damage caused by moisture and water infiltration.
During the Ottoman period, the faces of the four six-winged cherubim were hidden by metal coverings. One was restored and exposed in 2009. The western pair had not survived and were reconstructed as frescoes during the Fossati restoration.
Ottoman additions
Minarets and structural supports
The Ottoman complex includes four minarets, a mihrab, a minbar, sultan’s and imperial lodges, mausoleums, a madrasa, a library, a soup kitchen, an ablution fountain, and a clock building. The four minarets rise about 60 metres and use brick, limestone, and sandstone. Byzantine and Ottoman buttresses support the building. Some western external buttresses belong to the Byzantine period, while many others were added under Mimar Sinan. Approximately twenty-four buttresses were installed over the building’s history.
Furnishings and memorials
Two large alabaster vessels from Pergamon were installed on either side of the nave during the reign of Murad III. Each was carved from a single block of marble and used for ritual ablutions. The complex also contains the visible cenotaph marking the probable former burial place of Enrico Dandolo. The original tomb was destroyed after the Ottoman conversion, while the nineteenth-century marker remains.
Subterranean structures
Archaeological and geophysical investigations have identified structures beneath Hagia Sophia, including a natural rock slope, concealed spaces that may have helped absorb earthquake forces, and an early Byzantine underground network. These features have been examined further during recent restoration work, alongside the building’s supporting pillars and other structural connections.
