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Events on Tuesday 31 December 537 1
537Hagia SophiaIstanbul, Turkey — Honourable MentionBuilt in just five years by Emperor Justinian I, the Hagia Sophia in Constantinople was the largest cathedral in the world for nearly a thousand years. Its revolutionary 182-foot-high dome appeared to float on a ring of windows. Justinian reportedly exclaimed at its completion: 'Solomon, I have surpassed thee!' It served as a church, then a mosque, then a museum, and was reconverted to a mosque in 2020.