I was trying to get a close look at the western turrets added to the Hagia Sophia in the 16th century CE by Mimar Sinan (featured photo) when I realized that I was looking at four buttresses to the church. I stepped back a little to photograph them in their entirety (below) and realized that they were actually flying buttresses. I’d thought that they were invented in the 12th century in France, so this surprised me.
Hagia Sophia is remarkably stable, given the frequency of earthquakes in Istanbul. Over 1500 years, the dome has had to be rebuilt only twice. A large part of this stability is due to the geometric design of the dome, with its supporting half domes built atop a central square section. However, recent studies found that the improperly cured bricks and mortar miraculously make the structure stronger than properly cured bricks of the 6th century would have. This is likely to be an accident of the hurried construction of the church, rather than deliberate materials science, especially since this technique was not used in any other Byzantine structure. Even with this fortunate accident, the pressure of the huge dome would have caused the structure to collapse if it were not for buttresses added over the years.
The four flying buttresses on the western facade, which you see in the photo above, are remarkable. They look like they are, at least in part, made of the same material as the rest of the western facade. This was rebuilt in 994 CE, within five years of its collapse during the earthquake of 989 CE. So I wondered whether the flying buttress was invented by the Byzantines before the French. The older view is stated clearly in this paper from 1935, “… we can at once discard any hypothesis which would date these buttresses to the ninth century, for the simple reason that flying buttresses were unknown before the twelfth century”. This paper buttresses this erroneous reasoning with an aesthetic judgement that these four are different from “ungainly masses” which were erected by Byzantine and Turkish architects, and so must have been made by French engineers who arrived here during the Venetian occupation.
The modern view is different. Flying buttresses have been discovered in buildings in Cyprus which were buried in the 8th century CE, well before its reinvention in France. So these buttresses which puzzled me could have been a Byzantine construction from the 10th century CE. In a structure as old as the Hagia Sophia, one seldom has a clear answer to questions of provenance unless there is contemporary documentation. For these four there is none, although the circumstantial evidence is that the buttresses are about a thousand years old. This raises the inverse question, could the engineering idea of flying buttresses, which began to be used from the 12th century in western Europe, have been carried there from Byzantium?