Rome is the capital of Italy and of the Lazio region. It's the famed city of the Seven Hills, La Dolce Vita, Vatican City and Three Coins in the Fountain. Its Historic Center is a UNESCO World Heritage Site. Rome has more than 2.7 million residents and the metropolitan area has a population of about 4 million. It is located in the central-western portion of the Italian peninsula, where the river Aniene joins the Tiber. The city of Rome surrounds the Vatican City, the enclave of the Holy See, which is a separate sovereign state. It hosts Saint Peter's Square with the Saint Peter's Basilica. One of the symbols of Rome is the Colosseum, the largest amphitheatre ever built in the Roman Empire. The list of the very important monuments of ancient Rome includes the Roman Forum, the Pantheon, the Trajan's Column, the Palazzo Venezia, the Pallazzo Farnesse, the Palazzo Chigi, the Piaza Novana, the Piazza di Spagna,the Piazza Venezia, the Fontana di Trevi, the Monument of Vittorio Emanuelle II, the Castel Sant'Angelo and others. The Colosseum owes its name to a colossal bronze statue, representing the Emperor Nero, more than 35 m. tall, that used to stand in this area. Symbol of Rome worldwide, the Colosseum was built by the emperors of the Flavian dynasty between 72-80 A.D. The Roman Forum, the most important archaeological area in Rome, extends from the Capitol Hill to the Palatine. As far back as the 7th century B.C., the Forum was the centre of political, commercial and religious life. Later on, to the original Roman Forum were added the Imperial Forums: Foro di Cesare, Foro di Augusto, Foro di Nerva, Foro di Vespasiano and the most imposing one, the Foro di Traiano, of which one can still admire the huge Column of the Markets. Castel Sant'Angelo is the unique monument houses the National Museum where, besides the stuccoes, frescoes and furniture of the papal apartments, one can also admire an important collection of ancient arms. Castel Sant'Angelo is well known to Opera lovers. The Pantheon is an impressive example of the exquisite architectural technique of ancient Rome. It consists of a huge cylindrical body of equal height and width, covered by a great hemispherical dome.