Rome is the capital of Italy and also of the Province of Rome and of the region of Lazio. With 2.7 million residents in 1,285.3 km2, it is also the country's largest and most populated comune and fourth-most populous city in the European Union. Vatican City is an independent country within the city boundaries of Rome, the only existing example of a country within a city. Rome's history spans more than two and a half thousand years, since its legendary founding in 753 BC. It is referred to as "The Eternal City", a notion expressed by ancient Roman poets and writers. In the ancient world it was successively the capital city of the Roman Kingdom, the Roman Republic and the Roman Empire.