Why is istanbul famous?

Why is istanbul famous?
Istanbul is a very old city, originally founded as a trading city by the ancient Greeks and called Byzantium. Later, the first Christian emperor of the Roman Empire (Constantine) renamed it after himself (Constantinople) and moved the capital of the Roman Empire there from Rome. Later, after the fall of Rome it became the capital of the Eastern Roman (Byzantine) Empire for almost a thousand years until it was captured by the Ottoman Turks, renamed Istanbul, and it was their capital until the collapse of the Ottoman Empire in World War 1. After that Istanbul remained the capital of Turkey, and so it is today. It is a very famous city with a long history.