the third capital of Italy. The needs of the new capital led to an explosion both in the urbanisation and in the population within and outside the Aurelian walls. In 1874, a fifteenth rione, Esquilino, was created on the newly urbanised zone of Monti. At the beginning of the 20th century other rioni were created (the last one was Prati – the only one outside the Walls of Pope Urban VIII – in 1921). Afterwards, for the new administrative subdivisions of the city, the term "quartiere" was used. Today all the rioni are part of the first Municipio, which therefore coincides completely with the historical city (Centro Storico). Metropolitan and regional government Rome is the principal town of the Metropolitan City of Rome, operative since 1 January 2015. The Metropolitan City replaced the old provincia di Roma, which included the city's metropolitan area and extends further north until Civitavecchia. The Metropolitan City of Rome is the largest by area in Italy. At , its dimensions are comparable to the region of Liguria. Moreover, the city is also the capital of the Lazio region. National government Rome is the national capital of Italy and is the seat of the Italian Government. The official residences of the President of the Italian Republic and the Italian Prime Minister, the seats of both houses of the Italian Parliament and that of the Italian Constitutional Court are located in the historic centre. The state ministries are spread out around the city; these include the Ministry of Foreign Affairs, which is located in Palazzo della Farnesina near the Olympic stadium. Geography Location Rome is in the Lazio region of central Italy on the Tiber () river. The original settlement developed on hills that faced onto a ford beside the Tiber Island, the only natural ford of the river in this area. The Rome of the Kings was built on seven hills: the Aventine Hill, the Caelian Hill, the Capitoline Hill, the Esquiline Hill, the Palatine Hill, the Quirinal Hill, and the Viminal Hill. Modern Rome is also crossed by another river, the Aniene, which flows into the Tiber north of the historic centre. Although the city centre is about inland from the Tyrrhenian Sea, the city territory extends to the shore, where the south-western district of Ostia is located. The altitude of the central part of Rome ranges from above sea level (at the base of