558: The dome of the Hagia Sophia cathedral in Constantinople collapses following an earthquake.

Built by the decree of Eastern Roman Emperor Justinian, the Hagia Sophia was completed in 537, only five years after construction began. Given the scope of the ambitious project, it turned out to be something of a rush job, a fact that has plagued the building over the centuries.

Justinian intended the cathedral to stand as the ultimate symbol of his empire’s Byzantine Christian faith, and its design, both in concept and scale, was unprecedented. The massive dome rises 210 feet above the floor and has a diameter of 110 feet. The original architecture proved unstable for handling so large a structure.

Following two other partial collapses of the dome, the Hagia Sophia was reinforced with four large buttresses to provide better stability. The dome and the buttresses remain the building’s outstanding characteristics to this day.

The Hagia Sophia remained a jewel in the crown of Eastern Christendom and the see of the Patriarch until 1453, when Mehmet the Conqueror, the Ottoman sultan, took Constantinople and converted the cathedral into a mosque. It would remain an Islamic holy place until 1935 when it was converted again, this time into a museum, by the secular Turkish state.

Evidence of both its Christian and Muslim past resonate in the building to this day. In a city of landmarks, the Hagia Sophia, or Ayasofya, is perhaps modern Istanbul’s most famous.

(Source: Byzantines.net)