In Constantinople, the dome of the Hagia Sophia collapses, twenty years after its construction. Justinian I immediately orders that the dome be rebuilt.

Constantinople was a historical city located on the Bosporus, which served as the capital of the Roman, Byzantine, Latin, and Ottoman empires between its consecration in 330 and the formal abolition of the Ottoman sultanate in 1922. Constantinople was founded in 324, initially as New Rome, during the reign of Constantine the Great on the site of the existing settlement of Byzantium and in 330 became the capital of the Roman Empire. Following the collapse of the Western Roman Empire in the late 5th century, Constantinople remained the capital of the Eastern Roman Empire, the Latin Empire (1204–1261), and the Ottoman Empire (1453–1922). In the aftermath of the Turkish War of Independence, the Turkish capital moved to Ankara. The city was officially renamed Istanbul on 28 March 1930. As of December 2025, it is the most populous city in Europe, with a population of more than 16 million residents, straddling the Bosporus Strait and lying in both Europe and Asia, and is the financial centre of Turkey.