Built as a wooden-roofed basilica on the first of Istanbul’s seven hills and known as the ‘Great Church’ at that time, the opening of this structure took place in the year 360 during the reign of Emperor Constantine II. Following a fire that broke out during a rebellion in the year 404, causing extensive damage, there are no remaining remnants of this structure that have reached our times.

The second Hagia Sophia was built on top of the first by Emperor Theodosius II and opened for worship in the year 415. This structure, again in the form of a basilica with a wooden roof, was burned and destroyed by the rebels during the Nika Revolt against Emperor Justinian in the year 532. Emperor Justinian immediately decided to build a much larger and grander Hagia Sophia than the previous two after the revolt. The third Hagia Sophia was constructed by Byzantine Emperor Justinian I between the years 532 and 537. Used as the Imperial Church of the Eastern Roman Empire, Hagia Sophia has suffered frequent destruction throughout history due to revolts, wars, and natural disasters. One of the greatest destructions Hagia Sophia faced was during the Fourth Crusade in 1204 when the city was invaded. The Crusaders pillaged Hagia Sophia along with the entire city. During the period of Latin occupation in Istanbul from 1204 to 1261, Hagia Sophia was converted into a cathedral under the authority of the Roman Catholic Church. Having suffered serious damages, Hagia Sophia attempted to be preserved through repairs after the restoration of Byzantine rule in Istanbul. However, these repair efforts proved inadequate, and in the year 1346, a section of the eastern arch and the dome collapsed.

Since the time of Fatih Sultan Mehmed Khan, the Ottomans showed great care for Hagia Sophia Mosque, which they considered a symbol of the conquest, and they consistently carried out maintenance and repair activities to strengthen the mosque’s structure. Particularly, the additions and arrangements made by Architect Sinan in Hagia Sophia played a crucial role in the preservation of this human heritage that still stands today.

Fatih Sultan Mehmed Khan, who endowed Hagia Sophia Mosque as his charitable act and secured maintenance and repair costs by endowing numerous properties, initially commissioned a madrasa (religious school) to be built next to the mosque to initiate educational activities. The first minaret of Hagia Sophia was also constructed from wood during the reign of Fatih Sultan Mehmed Khan. This minaret, which lasted for many years, was removed during a major repair in 1574. The second minaret of Hagia Sophia Mosque was built from brick during the reign of Bayezid II. One of the Ottoman sultans who showed great interest in Hagia Sophia was Sultan Selim II. One of the Ottoman sultans who showed great interest in Hagia Sophia was Sultan Selim II. Upon the signs of wear and tear on the building, Sultan Selim II assigned Architect Sinan to take charge of the maintenance and repair of Hagia Sophia. Having suffered numerous collapses of its domes and walls during the Eastern Roman period, Hagia Sophia remained standing even after many significant earthquakes in Istanbul following the modifications by Architect Sinan. The construction of sultan’s tombs around Hagia Sophia was initiated with the construction of the first tomb by Architect Sinan in the cemetery of the Hagia Sophia Complex