Hagia Sophia has lived four lives in one building: cathedral, mosque, museum and mosque again, each change marking a turning point in the city’s history. Its dome, carried on curved pendentives rather than solid walls, solved a structural problem earlier builders had not managed, and the solution shaped domed architecture across three later traditions.
At a glance
Hagia Sophia, meaning Holy Wisdom and known in Turkish as Ayasofya, stands in the Fatih district of Istanbul. Built as a Christian cathedral in the sixth century, it became an Ottoman mosque after the conquest of Constantinople in 1453, was turned into a secular museum under Atatürk in 1934, and was reconverted to a mosque by presidential decree in July 2020, a decision that drew criticism from UNESCO and international religious bodies.
It forms part of the Historic Areas of Istanbul, inscribed as a UNESCO World Heritage Site in 1985. The building’s chief distinction is engineering rather than decoration alone: the dome, raised on pendentives that transfer its circular weight down onto a square base, was the largest in the world for centuries and directly influenced later Ottoman mosques in Istanbul.
Key facts
- Built: 532–537 CE, under Emperor Justinian I, by the architects Anthemius of Tralles and Isidore of Miletus; consecrated on 27 December 537.
- Dome: 31.87 metres in diameter and 55.6 metres above the floor, the largest dome in the world from its completion until Brunelleschi finished the dome of Florence Cathedral in 1436.
- Four phases: cathedral from 537, mosque from 1453, secular museum from 1934, mosque again from July 2020.
- Mosaics: the surviving Byzantine mosaics date from the ninth to the fourteenth centuries and include the Deësis mosaic and four large seraphim figures at the base of the dome.
- Restoration: major campaigns were carried out by Gaspare Fossati in 1847 and Wilhelm Salzenberg in 1854, with conservation work continuing since.
- Heritage status: part of the Historic Areas of Istanbul, a UNESCO World Heritage Site inscribed in 1985.
History
The site had already carried two earlier churches before the present building. The first was built under Constantius II in the fourth century and burned down in 404. Its successor was destroyed in the Nika riots of January 532, a violent uprising in Constantinople that devastated much of the city. Justinian I commissioned the present church immediately afterwards, and it was built in under six years by Anthemius of Tralles and Isidore of Miletus, an unusually fast construction for a large domed building of its time. The original dome collapsed in an earthquake in 558 and was rebuilt with a steeper profile by Isidore the Younger.
The sixth-century mosaics were destroyed during the Byzantine Iconoclasm between 726 and 843; the mosaics visible today date from the ninth to fourteenth centuries, made after images were permitted again. When Sultan Mehmed II entered Constantinople on 29 May 1453 he went to Hagia Sophia the same day and ordered its conversion into a mosque. Minarets were added over the following century, and Islamic medallions bearing the names of Allah, Muhammad and the first four caliphs were hung in the nave in 1847.
In 1934 Atatürk signed the decree making Hagia Sophia a secular museum, a founding gesture of Turkish secular modernism. It remained a museum until July 2020, when a presidential decree reconverted it into a working mosque, a move that attracted international criticism, including from UNESCO.
What you see
The building is entered from the south-west, with four Ottoman minarets, added between 1453 and 1574, framing the central dome. Inside, the dome rests on pendentives, curved triangular sections that allow a circular dome to sit on a square base, a solution that solved the central structural problem of Byzantine architecture. A ring of forty windows at the base of the dome lets in light that visually separates the dome from the walls beneath it, an effect the sixth-century historian Procopius of Caesarea described as making the dome appear suspended from heaven by a golden chain.
In the upper gallery is the Deësis mosaic, showing Christ flanked by the Virgin Mary and John the Baptist, notable for its relatively naturalistic rendering of the face of Christ. At the base of the dome are four large seraphim mosaics; two of these, previously covered by Ottoman medallions, were uncovered during restoration work between 2009 and 2010. Islamic calligraphic medallions from the nineteenth century remain in place in the nave alongside the surviving Byzantine mosaics.
Practical information
- Access: entry has been free since the building’s reconversion to a mosque in 2020; visitors are directed to designated areas during prayer times.
- Visiting hours and any restrictions: check the official channels for Hagia Sophia before travelling, as arrangements around prayer times can change.
- Dress and conduct: as an active mosque, modest dress and appropriate behaviour are expected of all visitors.
Getting there
Hagia Sophia stands in the Fatih district of Istanbul, in the historic heart of the city.
Nearby
- Blue Mosque (Sultanahmet Mosque) — in the same historic quarter of Istanbul; built in 1616, its domes follow the pendentive structure pioneered at Hagia Sophia.
- Süleymaniye Mosque — elsewhere in Istanbul; completed in 1558, another major Ottoman mosque built on the same structural principle.
- Selimiye Mosque, Edirne — some distance from Istanbul, in the city of Edirne; completed in 1575 and regarded as the architect Sinan’s masterwork, again using pendentive construction.
Sources
- UNESCO World Heritage Centre (Historic Areas of Istanbul)
- Procopius of Caesarea
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