Hagia Sophia history: Justinian's church of 537, the dome that fell and was rebuilt, the mosque, the museum and the mosque again

Architecture · 4 September 2026

Hagia Sophia, the "Holy Wisdom", in Istanbul was built between 532 and 537 by the emperor Justinian as the cathedral of Constantinople, designed by the mathematician Anthemius of Tralles and the geometer Isidore of Miletus, and for nearly a thousand years it was the largest church in the world, with a dome 31 m across floating 55 m above the floor on four arches and pendentives, a solution no one had tried at that scale before or has surpassed in masonry since. The dome fell in 558 after earthquakes and was rebuilt 6 m higher in 563; the church was the seat of the Orthodox patriarch until the Ottoman conquest of 1453, when Mehmed II made it a mosque and added the minarets; Atatürk made it a museum in 1934, and in July 2020 Turkey made it a mosque again, with the mosaics of Christ and the Virgin covered during prayers. Below: the buildings before it, how it was built, the dome, the mosaics, the sieges and conversions, the numbers, visiting today, and the stories, with the style explained in Byzantine architecture.

The first two churches

The first Great Church on the site was dedicated in 360 under Constantius II, the son of Constantine, a timber-roofed basilica beside the imperial palace and the hippodrome; it burned in 404 in riots over the exile of the patriarch John Chrysostom. The second, built by Theodosius II and dedicated in 415, was a larger basilica, fragments of whose carved entrance, with lambs standing for the apostles, lie in the garden in front of the present building; it burned on 13 January 532 in the Nika riots, when the chariot factions of Constantinople rose against Justinian and half the city was destroyed before his general Belisarius killed 30,000 in the hippodrome. Justinian, who had considered fleeing and was stopped by the empress Theodora, began the new church 39 days later, on 23 February 532, and it was consecrated on 27 December 537: five years and ten months. He is said to have entered it and declared, "Solomon, I have outdone you." Hagia Sophia.

How it was built

• The designers. Not architects but scientists: Anthemius of Tralles, a mathematician and physicist who wrote on burning mirrors and conic sections, and Isidore of Miletus, a professor of geometry who edited Archimedes; Justinian chose them, the historian Procopius says, for their learning, and the building's geometry, a dome on a square within a rectangle, is a problem in solid geometry solved in brick.
• The plan. A rectangle 82 by 73 m, with a central square 31 m across under the dome, half-domes east and west carrying the space out to 76 m, aisles and galleries behind arcades on the north and south, and a narthex and outer narthex to the west: a basilica and a centralised domed church combined, which is the invention.
• Materials. Brick and mortar for the vaults and dome, thin bricks with thick beds of lime mortar that took years to cure, which is partly why the first dome failed; stone for the piers and walls; columns of green Thessalian marble and red Egyptian porphyry, some taken from the temples of Ephesus, Baalbek and Rome; marble revetment of eight colours on the walls, cut in book-matched slabs so the veining forms patterns; and gold mosaic on every vault, about four acres of it.
• Labour. Procopius gives 10,000 workers under 100 master builders, in two teams competing on the north and south sides; the money was the whole imperial revenue of the years, an estimated 20,000 pounds of gold.
• Speed. Five years for a building of this size was possible because the emperor wanted it, because the piers were built of stone while the vaults of brick went up fast, and because no time was allowed for the mortar to set, which the next twenty years paid for.

The dome

The problem of a round dome on a square base was solved with pendentives: four triangular pieces of sphere that rise from the corners of the square between the four great arches and meet in a circle on which the dome sits, carrying its weight down into four piers. Hagia Sophia's are the first at this scale, and the idea, taken up in Ottoman mosques, Renaissance churches and St Paul's, is the building's gift to architecture. The first dome, finished in 537, was shallower than the present one and pushed outward too hard; earthquakes in 553 and 557 cracked the arches, and on 7 May 558 the eastern arch and the dome fell. Isidore the Younger, nephew of the geometer, rebuilt it in 558–63 as a taller dome, 6 m higher and closer to a hemisphere, so that the thrust went down instead of out, with 40 ribs between 40 windows around its base, which make the dome seem, in Procopius's words about the first, "suspended from heaven by a golden chain". It is 31.2 m across, not a perfect circle, between 30.9 and 31.8 m, because the piers had spread, and 55.6 m above the floor. Parts fell again in 989 and 1346 and were rebuilt; the western arch and dome section of 989 was by the Armenian architect Trdat, who built the cathedral of Ani. The Ottoman architect Sinan added the heavy buttresses on the outside in the 16th century, which is why the exterior is so much less graceful than the inside.

The mosaics and the church, 537–1453

Justinian's church had gold mosaic with crosses and no figures; the images came after iconoclasm ended in 843: the Virgin and Child in the apse of 867, the archangels, the emperors bringing gifts over the doors, the Deësis of about 1261 in the south gallery, Christ between the Virgin and John the Baptist, which is the finest Byzantine mosaic anywhere, and the panels of Constantine IX and Zoe and of John II Comnenus and Irene. The church held the coronations of the emperors, the relics of the Passion, the "Great Church" liturgy that converted the envoys of Prince Vladimir of Kiev in 987, who reported that "we knew not whether we were in heaven or on earth", and, in 1054, the excommunication laid on the altar by the pope's legate that began the schism of the Eastern and Western churches. In April 1204 the Fourth Crusade took Constantinople and sacked the church, a prostitute dancing on the patriarch's throne, and the doge Enrico Dandolo was buried in it; the Latins held it as a Catholic cathedral until 1261. On 29 May 1453 the Ottomans broke into the city and the people who had taken refuge in the church were enslaved; Mehmed II entered the same afternoon, ordered it cleaned and converted, and prayed there on the Friday.

The mosque, the museum, the mosque

• 1453–1481. Mehmed II adds a wooden minaret, a mihrab set into the apse at an angle toward Mecca, a minbar and a madrasa; the mosaics are left, and painted over gradually in the following centuries.
• 16th century. Bayezid II and Selim II add brick and stone minarets, Sinan strengthens the building with buttresses and builds the tombs of Selim II, Murad III and Mehmed III in the garden; the four minarets are complete by 1574.
• 1847–49. Abdülmecid I has the Swiss Fossati brothers restore the building; they uncover, record and re-cover the mosaics, and hang the eight great roundels with the names of God, Muhammad and the caliphs, 7.5 m across, that still hang in the nave.
• 1931–34. Thomas Whittemore's Byzantine Institute of America uncovers the mosaics with Atatürk's permission; on 24 November 1934 the cabinet closes the mosque and opens the museum in February 1935.
• 1985. Listed by UNESCO as part of the Historic Areas of Istanbul; some 3.7 million visitors a year by 2019.
• 10 July 2020. The Council of State annuls the 1934 decree and President Erdoğan declares it a mosque; the first Friday prayer is on 24 July, with the mosaics of the apse and the Deësis screened by curtains during prayers and the floor carpeted. Since 2024 tourists enter by a separate ticket to the galleries only.

The numbers and visiting

• Size. 82 by 73 m; the dome 31.2 m across and 55.6 m high; 107 columns; the nave 70 m long.
• Time. 5 years and 10 months to build; 916 years as a church, 481 as a mosque, 86 as a museum.
• Records. The largest cathedral in the world until Seville in 1520; the largest dome in the world after the Pantheon until Florence in 1436.
• Visiting. Open as a mosque, free on the ground floor for worshippers with modest dress and shoes removed, closed to tourists during the five prayers; since January 2024 foreign visitors pay a fee, about 25 euros, for the upper galleries, where the Deësis and the imperial panels are, entered from a separate door; the ground floor and the apse mosaics are seen from above. Early morning avoids the queues; the Blue Mosque, Topkapı and the cistern are across the square. Women cover their hair inside.

Versions and theories

• Built in five years by angels. A 9th-century Byzantine legend has an angel showing Justinian the plan, guarding the site, and revealing the church's name; the five years and ten months are documented, and the speed explains the first dome's fall.
• The weeping column. A column in the north aisle with a hole worn by fingers is said to cure illness if the thumb turns a full circle in it while wet; it is a column sweating condensation.
• The priest in the wall. Legend says that at the fall of the city in 1453 a priest saying mass disappeared into the wall with the chalice and will come out to finish when the church is Christian again. Told in Greek Istanbul for five centuries.
• The doors are from Noah's Ark. The "Nice Door" of 838 is Roman bronze of the 2nd century BC from a temple in Tarsus; the emperor's door of oak is said to be from the Ark. It is oak.
• Are the mosaics being destroyed? No: since 2020 they are covered by curtains at prayer times and uncovered otherwise; the roundels and the carpet are the visible changes, and UNESCO monitors the site. The stone floor under the carpet and the wear of the galleries are the conservation worries.
• Is the dome about to fall? It has moved through 14 centuries of earthquakes, and the 1999 Izmit earthquake did not damage it; engineers who have modelled it find the buttressed structure surprisingly sound, and a large Istanbul earthquake is the risk for everything in the city, not this building especially.

The mosques that answered it, from Sinan's Süleymaniye to the Blue Mosque, are in Islamic architecture; its Roman ancestor in the dome is in Roman architecture.

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