Hagia Sophia (532-537): Building Justinian's Great Church

Hagia Sophia, the “Church of Holy Wisdom” in Constantinople, was rebuilt by the emperor Justinian I between February 532 and December 537 after rioters burned the earlier church during the Nika revolt. Designed by the mathematicians Anthemius of Tralles and Isidore of Miletus, it covered a vast open space with a dome that seemed to float above a ring of windows. For nearly a thousand years it was the cathedral of the Byzantine Empire and the most admired building in the Christian world, until it became a mosque after the Ottoman conquest of 1453.

Background: two earlier churches

The first great church on the site, known simply as the Great Church (Megale Ekklesia), was dedicated on 15 February 360 under the emperor Constantius II. It stood next to the imperial palace and the Hippodrome, in the ceremonial heart of the new capital. In 404 it burned during riots that followed the exile of the archbishop John Chrysostom.

A second church, built under Theodosius II, was dedicated on 10 October 415. It was a timber-roofed basilica, the usual form for large churches of the time, and some carved blocks from its entrance porch can still be seen in front of the present building.

That church was destroyed in January 532 in the Nika riots, when the Blue and Green circus factions rose against Justinian and set fire to the city centre (see Nika riots). Once the revolt was crushed, Justinian decided not merely to repair the cathedral but to build something unprecedented.

Planning and the architects

Construction began on 23 February 532, only some five weeks after the riots ended. Justinian chose as his designers Anthemius of Tralles, a mathematician who wrote on burning mirrors and conic sections, and Isidore of Miletus, a geometer and teacher. Procopius, who described the building in his Buildings, calls them mechanikoi, experts in applied mathematics, rather than ordinary master builders.

Their design combined two traditions: the long basilica, suited to processions, and the centralised domed building. The result was a nave roughly 70 metres long, crowned by a central dome on four great arches and extended east and west by two half-domes, which in turn opened into smaller semi-domes. Aisles and upper galleries ran along both sides.

The project was enormous and fast. Materials came from across the empire: white marble from the island of Proconnesus in the Sea of Marmara, green marble from Thessaly, red porphyry from Egypt and coloured stones from many quarries. Later Byzantine legends speak of 10,000 workers and fabulous costs, but no reliable figures survive.

The building was designed for imperial ceremony as well as worship. The emperor and patriarch entered together on great feast days, and a large marble pulpit, the ambo, stood in the centre of the nave for readings and sermons. The upper galleries were used by women and by the court, and the church was linked directly to the patriarch’s residence and, by processional routes, to the Great Palace next door.

The revolutionary dome

The central dome was the heart of the design. It rested on pendentives, curved triangular sections of masonry that carry a round dome over a square space below. Pendentives were not new, but nothing had been attempted with them on this scale.

The builders used brick set in very thick beds of mortar, which made the walls relatively light but slow to harden. As the structure rose quickly, the arches and piers began to deform outwards, and the builders had to adapt the design as they went. The 40 windows around the base of the dome flooded the interior with light, so that, as Procopius wrote, the dome seemed not to rest on solid masonry but to hang from heaven.

The building’s engineering has been studied intensively in modern times. Engineers have shown that the main piers and the great arches moved outwards during and after construction, and that the original dome’s shallow curve pushed hard on its supports. The structure has nevertheless survived many earthquakes, partly because its masonry and thick mortar joints can absorb movement, and partly because of centuries of repair and buttressing.

Inside, the surfaces were covered with coloured marble panels and gold mosaic. Justinian’s mosaics were mostly non-figurative, with crosses and patterns; the famous figural mosaics now visible were added after the end of Byzantine Iconoclasm in 843. The great mosaic of the Virgin and Child in the eastern apse was unveiled in 867 with a sermon by the patriarch Photios, and later panels show emperors such as Constantine IX and the empress Zoe in the eleventh century. The Deesis mosaic in the south gallery, showing Christ between the Virgin and John the Baptist, is usually dated to the late thirteenth century.

Dedication and the first collapse

Justinian dedicated the new cathedral on 27 December 537, less than six years after work began. It was the largest church interior in the Christian world and remained so for centuries.

The haste had a price. Earthquakes in August 553 and December 557 cracked the structure, and on 7 May 558 the eastern part of the dome and its arch collapsed. Isidore the Younger, nephew of Isidore of Miletus, designed a new dome with a steeper profile, roughly 6–7 metres higher than the first, which reduced the outward thrust. The church was rededicated in December 562, and the poet Paul the Silentiary celebrated it in a long verse description. This second dome, though repaired many times, is essentially the one that stands today.

Hagia Sophia in the Byzantine centuries

For more than 900 years Hagia Sophia was the seat of the patriarch of Constantinople and the setting for imperial ceremonies, including coronations. Its liturgy impressed visitors: according to the Russian Primary Chronicle, envoys of Prince Vladimir of Kyiv reported that in its services they did not know whether they were in heaven or on earth, a story linked to the conversion of the Rus around 988.

The church also saw momentous conflict. On 16 July 1054 the papal legate Cardinal Humbert placed a bull of excommunication against the patriarch Michael Cerularius on its altar, an event traditionally taken as the start of the split between the Catholic and Orthodox churches (see Great Schism of 1054). In 1204 soldiers of the Fourth Crusade looted the church, and it served as a Latin Catholic cathedral until the Byzantines retook the city in 1261.

Structural crises recurred. An earthquake in 989 brought down part of the dome, which the Armenian architect Trdat repaired by 994. Another partial collapse in 1346 took several years to repair. Buttresses added over the centuries now give the exterior its heavy, massive look.

The fall of Constantinople

On 29 May 1453 the Ottoman army of Sultan Mehmed II captured Constantinople, and many inhabitants took refuge in Hagia Sophia before it was broken into. The evening before, a final Christian service had been held there, attended by Orthodox and Catholic clergy and, according to tradition, by the last emperor, Constantine XI (see Fall of Constantinople). Mehmed converted the building into a mosque, and Friday prayers were held there within days.

The Ottomans added minarets, a mihrab and later large calligraphic roundels, and covered the figural mosaics over time rather than destroying them. Hagia Sophia’s plan deeply influenced Ottoman mosque architecture, above all the works of the architect Sinan in the sixteenth century. The building became a museum in 1935 and was reclassified as a mosque in 2020; it is part of the UNESCO World Heritage Site of the Historic Areas of Istanbul.

Myths and facts

Myth: Justinian cried “Solomon, I have outdone thee”. The saying appears in a legendary account of the building written several centuries later, not in any contemporary source.

Myth: Hagia Sophia is named after Saint Sophia. The name means “Holy Wisdom” and refers to the Wisdom of God, not to a saint.

Partly true: columns from ancient temples. Later tradition claimed that columns were brought from the Temple of Artemis at Ephesus and other famous sites. Some materials were reused, but these specific stories cannot be confirmed.

By the numbers

Timeline

• 15 February 360: First Great Church dedicated under Constantius II.
• 10 October 415: Second church dedicated under Theodosius II.
• January 532: Second church burned in the Nika riots.
• 23 February 532: Construction of Justinian’s church begins.
• 27 December 537: Hagia Sophia is dedicated.
• 7 May 558: The original dome partly collapses after earthquakes.
• December 562: The church is rededicated with Isidore the Younger’s higher dome.
• 16 July 1054: Papal legates lay a bull of excommunication on the altar.
• 1204–1261: Used as a Latin cathedral after the Fourth Crusade.
• 29 May 1453: Ottoman conquest; Hagia Sophia becomes a mosque.

Why it matters

Hagia Sophia was a technical and artistic leap that showed what late Roman engineering could achieve in a single burst of imperial will (see Justinian I). For a millennium it embodied Byzantine Christianity, and its dome shaped the architecture of churches and mosques from Russia to the Ottoman world.