The ancient name of Istanbul is Byzantium, which was later renamed Constantinople after the Roman Emperor Constantine the Great established it as the new capital of the Roman Empire in 330 AD. Byzantium was originally founded by Greek colonists from Megara in the 7th century BC. The city endured various cultural influences and transformations, ultimately serving as a critical center for trade, religion, and culture. In 1453, Constantinople fell to the Ottoman Empire and was eventually renamed Istanbul, reflecting its new Islamic identity while retaining a rich tapestry of its historical legacy.