In 306 CE, Constantine became emperor of the entire Roman empire, east and west, and decided to move the capital city from Rome to an old fortress city on the Bosphorus, then called Byzantium. He wanted it to be called New Rome but the city gradually adopted the name of Constantinople in his honor. Politics dictated that
soon the east and west would separate again, and the western portion of the Roman Empire fell to the Germanic tribes in 476 CE.