Hagia Sophia “[the church of] divine wisdom” was considered the greatest building achievement of all time. When it was finished the builder exclaimed: “I have outdone Solomon!” The dome was the largest in the world for almost a thousand years, until exceeded by a cathedral in Seville which opened in 1520. It started with the “magna ecclesia” in 360 (15th February, the date of my sister’s birthday! gulp) revamped under Theodosius II in 415 and then following the nikea riots in the hippodrome the wooden roof caught fire and the third edition was built, roughly in the form we see today. The riots appear to be a public resentment of the nepotism of Justinian and the excesses of Theodora (his wife). 30,000 of the opposition to Justinian were killed in what could only be described as a blood bath in the hippodrome. The nikea (after the call to conquer) riot having been suppressed, the emperor rebuilt much of Constantinople, using material from all around the empire, including columns from the temple of Artemis at Ephesus (explaining the absence of any real ruins at the current site)
This was the capital of the eastern roman empire. The eastern empire commenced under Constantine, with the then capital known as Constantinople, or the city of Constantine. The separation into two legs was featured by diverse views on such religious items as icons. Determined to be an idol if the thickness exceeded a set rule, the zealots of this idea scourged the roman world destroying idols within the churches and became known as iconoclasts. The icons became spectacular in their deciptions, and the wealth and art value seen as a token of the authority of the church
Emperor Justinian commissioned the reconstruction of the church, being built between 5327-537, and other relics of his time are still visible in Istanbul, eg the Basilica cisterns., noted for the pillars with greek mythology (esp Medusa) scavenged from earlier constructions.
The original roman decorations in the main were covered over with arabic script and items devoted to the Koran as seen in the following images