What Is Hagia Sophia & Who Built It?

The Hagia Sophia was built by the Roman emperor Justinian I in 537 CE as a grand cathedral in Constantinople, now Istanbul.

May 30, 2024By Vedran Bileta, MA in Late Antique, Byzantine, and Early Modern History, BA in History

what is hagia sophia


The Hagia Sophia is an architectural marvel and one of the most sacred places in two major world religions. Constructed under the orders of the Roman emperor Justinian I in 537 CE, Hagia Sophia, or a “Church of Divine Wisdom”, served as the world’s largest Christian cathedral for nearly a thousand years. Located in the heart of the Byzantine Empire in Constantinople (now Istanbul), Hagia Sophia was the site of imperial coronations and the seat of the orthodox patriarch until the fall of the city to the Ottomans in 1453. Following the conquest, Hagia Sophia was converted into a mosque, retaining its status until 1935, when it became a museum. Since 2020, Hagia Sophia is a mosque once again. Nonetheless, Hagia Sophia remains a remarkable building, a testament to Justinian’s ambition and legacy. 


1. Hagia Sophia Is the Third Church Built on the Site

View of Hagia Sophia, Justinian’s grand cathedral, and one of the largest domed buildings in the world
View of Hagia Sophia, Justinian’s grand cathedral, and one of the largest domed buildings in the world


The Hagia Sophia is undoubtedly one of the most fascinating buildings in the world. However, Justinian’s grand cathedral is the third church built on the site. The first building, known as the “Great Church”, was built in the center of Constantinople, next to the imperial palace, and was consecrated in 360 CE during the reign of emperor Constantius II, son of Constantine the Great


In 404, during the riots, the “Great Church” perished in the flames. Almost immediately, emperor Theodosius II ordered the construction of the new church. The Theodosian basilica was completed in 415, but the name Hagia Sophia (“The Church of Divine Wisdom”) came into use around 430. This second church, too, met its fiery end in 532 CE during the infamous Nika Riot. It would be emperor Justinian, who built the present structure, the third Hagia Sophia, the largest Christian cathedral in the world.


2. Building Hagia Sophia Was the Massive Endeavour

byzantine emperor justinian mosaic
Detail from the imperial mosaic of Justinian I, Basilica of San Vitale in Ravenna, ca. 547 CE.


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After the imperial troops, led by general Belisarius, suppressed the Nika Riot, emperor Justinian immediately began rebuilding Constantinople. Determined to create a lasting symbol of his reign and the glory of the Roman Empire, Justinian commissioned the renowned architects Anthemius of Tralles and Isidore of Miletus to design and construct the current Hagia Sophia. 


The third church was designed to be grander and more resilient than its predecessors, incorporating advanced engineering techniques and architectural innovations of the time. The construction was a massive undertaking, employing thousands of workers and sourcing materials from all over the Empire, which had been significantly expanded through Justinian’s campaigns. The speed and scale of the project were remarkable, with the new cathedral completed in just five years, from 532 to 537 CE.


3. It Was a Political Statement

The mosaic from the Hagia Sophia, showing the Virgin Mary holding the Christ Child, flanked by the emperors Constantine and Justinian, holding the model of the city of Constantinople, and the church of Hagia Sophia, 9th century, Istanbul
The mosaic from the Hagia Sophia, showing the Virgin Mary holding the Christ Child, flanked by the emperors Constantine and Justinian, holding the model of the city of Constantinople, and the church of Hagia Sophia, 9th century, Istanbul


Hagia Sophia was not only the center of Christianity, but also a monumental testament to Justinian’s triumph, of his restored authority following the riots. It was also a clear demonstration of imperial power and challenge to the emperor’s rivals, including the supporters of the late emperor Anastasius. The Hagia Sophia was designed to eclipse another great cathedral in Constantinople – The Church of St. Polyeuctus – founded by wealthy noblewoman Anicia Juliana, a descendant of emperors Theodosius I and Constantine the Great.


Thus, the construction of the Hagia Sophia and Justinian’s famous exclamation, “Solomon, I have surpassed thee,” could be seen as a direct challenge to Anicia and her noble supporters. It was a bold political statement by Justinian, a low-born soldier, who was now the emperor and the founder of a new imperial dynasty.


3. Hagia Sophia Was an Engineering Marvel

golden dome hagia sophia
The massive Dome of Hagia Sophia, and the supporting pendatives. The mosaic of Christ Pantokrator is now lost, but one of archangel faces is still visible.


However, the symbol of Justinian’s power almost collapsed not long after its construction. Following a series of earthquakes that hit Constantinople, in 558 the original dome collapsed and had to be replaced with a new one. Finally, in 563 CE, the construction was completed, and Hagia Sophia got its present-day shape.


Hagia Sophia is rightly celebrated as an architectural and engineering marvel. Its massive central dome was a groundbreaking feat for its time. The innovative use of materials and techniques employed by its builders created a vast, column-free interior space that amplified the sense of heavenly grandeur. Despite numerous quakes that necessitated repairs in its long history, Hagia Sophia stood the test of time for centuries.


4. It Became the Epicenter of Byzantine Religious, Political and Cultural Life

portrait emperor john komnenos hagia sophia mosaic
The mosaic of John II Komnenos, and his wife, empress Irene (Piroska), present gifts to the Virgin Mary and Child, 1118, Hagia Sophia, Istanbul


Justinian died in 565 CE, but his great Church would outlive him, becoming the epicenter of Orthodox Christianity. For almost a millennium, Hagia Sophia served as the religious, political and cultural centre of the Empire: as the seat of the Patriarch of Constantinople, the coronation place of the Byzantine emperors, and a pivotal location for imperial and religious processions.


Hagia Sophia’s massive size and grandeur, with its immense dome and lavish mosaics, symbolized the power of the emperors – the vicegerents of God on Earth. The church played a vital role in imperial diplomacy, with countless embassies left in shock and awe following their visit to the greatest cathedral in all of medieval Christendom. Such is the case of the Rus, who were so stunned by the Hagia Sophia’s grandeur and beauty that they decided to convert to Orthodox Christianity.


5. Hagia Sophia Endured till the Present Day

Hagia sophia
The Hagia Sophia as seen today with the four minarets added during the Ottoman period


The Hagia Sophia’s architectural style and ornate decorations influenced the design of subsequent Orthodox churches throughout the Empire and beyond. It also impacted the mosques built by Islamic conquerors following the imperial catastrophe at Yarmouk in 636. Following the Fourth Crusade, the building briefly served as Roman Catholic church before being consecrated as Orthodox cathedral in 1261. Even after the Fall of Constantinople in 1453, Hagia Sophia’s legacy endured, embodying the spiritual and cultural heritage of Byzantium. 


Over the centuries, the role of the Hagia Sophia evolved to reflect Istanbul’s shifting political and religious landscape. During the Ottoman period, it became a mosque, with the addition of four minarets and other Islamic architectural features. The magnificent golden mosaics, depicting long-gone Roman emperors in the company of Jesus, Mary and Saints, were covered but not destroyed. These mosaics were later uncovered in 1935, when Hagia Sophia became a museum, allowing people of all backgrounds and beliefs to appreciate this masterpiece of art and architecture.


hagia sophia
Hagia Sophia, a lasting legacy of emperor Justinian I


However, in July 2020, the Turkish government decided to reconvert Hagia Sophia to the mosque, sparking international criticism. Yet, Hagia Sophia endures, a witness to one emperor’s ambition, vision, and determination: Justinian’s Great Cathedral.

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By Vedran BiletaMA in Late Antique, Byzantine, and Early Modern History, BA in HistoryVedran is a doctoral researcher, based in Budapest. His main interest is Ancient History, in particular the Late Roman period. When not spending time with the military elites of the Late Roman West, he is sharing his passion for history with those willing to listen. In his free time, Vedran is wargaming and discussing Star Trek.