Rome is the capital of Italy and of the Lazio region. Rome's history spans more than 2,500 years. The city's early population originated from a mix of Latins, Etruscans and Sabines. Eventually, the city successively became the capital of the Roman Kingdom, the Roman Republic and the Roman Empire, and is regarded as a the birthplace of Western civilisation and by some as the first ever metropolis. It was first called The Eternal City by the Roman poet Tibullus in the 1st century BC, and the expression was also taken up by Ovid, Virgil, and Livy. Rome is also called the "Caput Mundi" (Capital of the World). Rome ranked in 2016 as the 13th-most-visited city in the world, 3rd most visited in the European Union, and the most popular tourist attraction in Italy. Its historic centre is listed by UNESCO as a World Heritage Site. Monuments and museums such as the Vatican Museums and the Colosseum are among the world's most visited tourist destinations with both locations receiving millions of tourists a year.