Hagia Sophia

Hagia Sophia, whose Greek name means Holy Wisdom, is a great domed building on the old peninsula of Istanbul, formerly Constantinople. The present structure was built for the emperor Justinian I between 532 and 537 and was for nearly a thousand years the chief cathedral of the Byzantine Empire. After the Ottoman conquest of 1453 it became a mosque, then in 1935 a museum, and since 2020 it has again been a mosque. Few buildings have passed so visibly between faiths and states.

The first church on the site was consecrated in 360 under the emperor Constantius II; a later tradition crediting Constantine the Great is not attested before the seventh or eighth century. That church largely burned in 404 during riots that followed the exile of the patriarch John Chrysostom. A second church, dedicated by Theodosius II in 415, was in turn destroyed by fire in January 532 during the Nika riots, a violent uprising that began among the chariot-racing factions of the Hippodrome.

Within weeks Justinian began a far larger building. His architects, Anthemius of Tralles and Isidore of Miletus, designed a basilica crowned by an enormous central dome. More than 10,000 people are said to have worked on it, and it was inaugurated on 27 December 537. According to a much-repeated story, Justinian declared on seeing it that he had surpassed Solomon. Earthquakes in 553 and 557 cracked the dome, and part of it collapsed in 558. Isidore the Younger rebuilt it about 6 metres higher with a lighter ribbed design, and the church was rededicated in 562. The dome measures about 32 to 33 metres across, and the interior rises some 55 metres. For more than five centuries it was the largest interior space in the world.

In the eighth and ninth centuries, during the period of Iconoclasm, religious images were removed from the church. Earthquakes brought down parts of the building in 869, 989 and 1346, each followed by repairs. In 1054 a papal envoy laid a bull of excommunication against the patriarch Michael Cerularius in the church, an act traditionally taken as the start of the schism between the Eastern and Western churches.

During the Fourth Crusade in 1204 crusaders looted and desecrated the building, and the crusader leader Baldwin I was crowned emperor there. The Venetian doge Enrico Dandolo was buried inside. Byzantine Orthodox rule returned in 1261. On 29 May 1453 Constantinople fell to Mehmed II, who ordered the church to be turned into a mosque, and he attended Friday prayers there on 1 June.

Under the Ottoman Empire the building gained minarets, the first built in the late fifteenth century. In the reign of Selim II, between 1566 and 1574, the architect Mimar Sinan strengthened it with external buttresses and added minarets and a tomb. Later sultans built a library, a school and a fountain within the complex. Mosaics were covered with plaster, which helped preserve some of them. Between 1847 and 1849 Sultan Abdulmejid I employed the Fossati brothers to carry out a major restoration, during which eight huge round panels bearing the names of God, the Prophet Muhammad, the first four caliphs and his grandsons Hasan and Husayn were hung in the nave.

The building was closed in 1931, and in 1935, under the republic led by Mustafa Kemal Atatürk, it reopened as a museum. Its surviving mosaics include the Deesis, probably made around 1261 and widely considered the finest in the building. In 1985 UNESCO listed it as part of the Historic Areas of Istanbul World Heritage Site. By 2014 it drew about 3.3 million visitors a year.

On 10 July 2020 Turkey's Council of State annulled the decision that had made it a museum, and President Erdoğan ordered it reopened for Muslim worship. The first Friday prayers were held on 24 July. The change was welcomed by some Muslim leaders and condemned by the Turkish opposition, the World Council of Churches and others. UNESCO expressed regret that it was made without prior discussion and asked for reports on the site's conservation, while Turkey said the changes had no harmful effect. During prayers the Christian images in the apse are now veiled with curtains. A major programme to strengthen the dome against earthquakes began in 2025.