Constaninople was the name for the city which changed its name to Istanbul in 1930. It was renamed Constantinople by the Roman Emperor Constantine I; formerly, as a colony of classical Greece it was known as Byzantium.
Straddling the Bosporus it holds the unique distinction of being in two different continents at once.
Constantinople was the centre of the Byzantine Empire, until its fall in 1453 when it became part of the Ottoman Empire. The city was infamously sacked by the Fourth Crusade in 1204, but members of the Comnenus family, who had provided Emperors of Byzantium, had by then established a refuge empire at Trebizond. In 1261, after the Latin Empire had dwindled, the city was retaken by the Byzantines, who moved their Empire back in.