Istanbul—a metropolis of over 15 million inhabitants—is one of the world's most populous cities, and thus, naturally, Turkey's largest and most important city, both economically and culturally. Indeed, Istanbul remains one of the oldest cities in the world. It was the capital of the Roman Empire between 330–395 AD, the Eastern Roman Empire between 395–1204 AD and between 1261–1453 AD, the Latin Empire between 1204–1261 AD, and finally the Ottoman Empire between 1453–1922 AD.