Hagia Sophia
Seeing a great building is a fascinating experience. By a great building, in this case I mean one that is historic (there is quite a different commentary to be made about seeing a new but equally extraordinary construction, like one of the new Guggenheim museums). To be clear, there are two reasons to consider a building as ‘great’: first there are those considered so because of their history, the events in which they have played a part, the people with whom they’ve been associated; and second, those that are great in their own right, architecturally compelling and internally rich in such ways as to be striking, imposing, or simply intriguing. Quite often the attraction of historic great buildings lies in the stories in which they played a part, the past events in which they were implicated, or even those which were based at home, a resting place or a meeting place, places that mattered in the conduct of human affairs.
This building, the Hagia Sophia, has been important for centuries, as a religious centre, as a landmark, and as a meeting place. The photograph shows it in 2025, with one of its minarets under repair. If it’s only seen from the outside, the building offers only a limited sense of its amazing interior, and the history that interior reveals. To the casual external observer, it is big, somewhat squat, with some evidence of its complicated past. Briefly, from around 360 AD through to 1453 AD (with a few minor interruptions), it was a major Eastern Orthodox church, the greatest in Christendom, with a dome that was unequalled until Brunelleschi’s in Florence in the 15th Century. One of the Hagia Sophia’s interruptions was between 1204 and 1261 when for a short time it became a Roman Catholic church. Following that, from 1453 to 1934, it was a Sunni Moslem mosque. Then, in 1935 it was deconsecrated and became a museum, a major attraction for visitors to Istanbul. In 2020 it reverted back to being a Sunni mosque once more, but this time one that is still allowing tourists to visit.
For those who might be hoping for a kind of striking beauty, outside it appears to be rather big but not especially graceful. One of the minarets was under refurbishment in 2025 which was somewhat disconcerting to those who want their travel photographic images to mirror some kind of unrealistic form of perfection. The reality of repair got in the way! There are gardens around the building, nicely tended, but unremarkable. More to the point, the few trees tin the gardens gave rather little shade, in a location that is often hot, and sometimes unrelentingly so. It is only on entering that you realise the true beauty is inside.
What you see was built by Justinian 1 between 532 and 537 AD and was formerly called the Temple of God’s Holy Wisdom. It was the world’s largest cathedral for nearly a thousand years, and was considered as the quintessential example of Eastern Orthodox church design. In various iterations it was to remain a religious centre until 1931, when it was closed to the public, only to re-open in 1935 as a museum. In 2020, it was reclassified back as a mosque, a controversial decision which remains widely debated. As a major tourist attraction, visitors today can freely enter the first floor of the building, but the ground floor is restricted to worshippers and their invitees.
It is impossible to briefly describe the many features of the Hagia Sophia. It is regarded as one of the greatest surviving examples of Byzantine architecture. It used masonry in its construction, but it is the decorations inside that have ensured its fame. The interior is decorated with mosaics, marble pillars, paintings, and other items of great artistic value. As it was being constructed in the Sixth Century AD, Justinian achieved his vision by his determination to oversee the completion of what was to be the greatest cathedral ever built up to that time. The basilica was simultaneously the culminating architectural achievement of late antiquity together with being recognised as a masterpiece of Byzantine architectural style. Its influence, both physically and liturgically, has been widespread and enduring .
Of particular interest is the complex structure of the vast interior. The central nave is covered by a huge dome, which rises to 55.6 metres (182 ft 5 in) above floor level and rests on an arcade of 40 arched windows. Not perfect, however, as repairs to its structure have left the dome somewhat elliptical, with the diameter varying between 31.24 and 30.86 metres (102 ft 6 in and 101 ft 3 in). At the western entrance and along the eastern liturgical side, there are arched openings extended by half domes of identical diameter to the central dome, built up to create an overall vast oblong interior crowned by the central dome with its uninterrupted span of 76.2 metres (250 ft).
The overall design is clearly geometric and is said to be based on mathematical formulae from Heron of Alexandria, which avoided the use of irrational numbers for its construction. Research suggests the architects used Hero’s proposed values for constructing the vaults. The measurements were calculated using a side-and-diagonal number progression, which results in squares defined by the numbers 12 and 17, with 12 defining the side of the square and 17 its diagonal, numbers which had been used as standard values as early as cuneiform Babylonian texts. Each of the four sides of the great square at the centre is approximately 31 metres long, previously thought to be the equivalent of 100 Byzantine feet. However recent research has determined the side of the central square of Hagia Sophia is not 100 Byzantine feet but instead 99 feet. This measurement is not only rational, but it is also embedded in a system of number progression (70/99) used in the applied mathematics of antiquity.
Over the centuries, there have been restorations and enhancements. One remarkable moment was in 1453 when 21 year old Mehmet II decided not to obliterate all the mosque’s Christian mosaics when he conquered Constantinople: he was not there simply to destroy. Another and more recent phase was the 19th-century restoration ordered by Sultan Abdulmejid I, which was completed between 1847 and 1849 by eight hundred workers supervised by the Swiss-Italian architect brothers, Gaspare and Guiseppi Fossati. Given concerns about stability and evident slippage, the brothers consolidated the dome with a restraining iron chain. At the same time they strengthened the vaults, straightened the columns, and revised the decoration of the exterior and the interior of the building. Upper gallery mosaics were exposed and cleaned, but many were re-covered ‘for protection against further damage’.
Restoration did more than preserve. Eight new gigantic circular-framed discs were hung from the cornices on each of the four piers on either side of the apse and the west doors, designed by Kazasker Mustafa Izzet Efendi, and emblazoning the names of Muhammad, Allah, the first four caliphs and the two grandsons of Muhammad. They are simply stunning.
Given continuing deterioration and problems, the need for restoration continued, aggravated by decisions like those during in the Second World War when the minarets of the mosque housed machine guns! Sadly, today the condition of the structure continues to deteriorate, and it was included in the 1996 and 1998 Watch Lists of the World Monuments Fund. The building’s copper roof had cracked, causing water to leak down over the fragile frescoes and mosaics. Moisture entered from below, increasing the humidity level within the mosque. Work has been undertaken to repair of the cracked roof, and preserve the dome’s interior. Despite all the care that has been shown, major problems remain. Most experts have concluded the dome will collapse soon, a tragic outcome signaling the end of this remarkable building. Thrilling to see, the Hagia Sophia is close to the end of its life, unless amazing and unlikely efforts are made to save it: indeed some suspect it might collapse before 2040.
