Original: In its long history , Istanbul has served as the capital city of the Roman Empire ( 330 -- 395 ) , the East Roman ( Byzantine ) Empire ( 395 -- 1204 and 1261 -- 1453 ) , the Latin Empire ( 1204 -- 1261 ) , and the Ottoman Empire ( 1453 -- 1922 ) .
Simplified: When the Roman Empire was later divided into two , the East Roman Empire was known as the Byzantine Empire , and had its capital in Constantinople .