Rome is the capital city of Italy and Lazio, and is Italy's largest and most populous city, with 2,705,317 residents,an urban area of 3,457,690 as well as a metropolitan area of about 4 million inhabitants spread over a 5,352 km² area. It is located in the central-western portion of the Italian peninsula, on the Tiber river.

Rome's history as a city spans over two and a half thousand years, as one of the founding cities of Western Civilisation. Even outside of the history of the Roman Empire, Rome has a significant place in the story of Christianity up to the present day as the home of the Roman Catholic Church.

As one of the few major European cities that escaped World War II relatively unscathed, central Rome remains essentially Renaissance and Baroque in character. Rome is the third-most-visited tourist destination in the European Union, and its historic centre of Rome is listed by UNESCO as a World Heritage Site.

Rome is in the Lazio region of central Italy on the Tiber river (Italian: Tevere). The original settlement developed on hills that faced onto a ford beside the Tiber island, the only natural ford of the river. The historic centre of Rome 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. The city is also crossed by another river the Aniene which joins the Tiber north of the historic centre.

Although the city centre is about 24 km (14.9 mi) 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 13 m (43 ft) above sea level (at the base of the Pantheon) to 139 m (456 ft) above sea level (the peak of Monte Mario). The Commune of Rome covers an overall area of about 1,285 km2 (496 sq mi), including many green areas.

Throughout the history of Rome, the urban limits of the city were considered to be the area within the city walls. Originally, these consisted of the Servian Wall, which was built twelve years after the Gaulish sack of the city in 390 BC. This contained most of the Esquiline and Caelian hills, as well as the whole of the other five. Rome outgrew the Servian Wall, but no more walls were constructed until almost 700 years later, when, in 270 AD, Emperor Aurelian began building the Aurelian Walls. These were almost 19 km (12 mi) long, and were still the walls the troops of the Kingdom of Italy had to breach to enter the city in 1870. Modern Romans frequently consider the city's urban area to be delimited by its ring-road, the Grande Raccordo Anulare, which circles the city centre at a distance of about 10 km.

The Commune of Rome, however, covers considerably more territory and extends to the sea at Ostia, the largest town in Italy that is not a commune in its own right. The Commune covers an area roughly three times the total area within the Raccordo and is comparable in area to the entire provinces of Milan and Naples, and to an area six times the size of the territory of these cities. It also includes considerable areas of abandoned marsh land which is suitable neither for agriculture nor for urban development.

As a consequence, the density of the Commune is not that high, the communal territory being divided between highly-urbanised areas and areas designated as parks, nature reserves, and for agricultural use. The Province of Rome is the largest by area in Italy. At 5,352 km², its dimensions are comparable to the region of Liguria, and more than three times the size of the greater metropolitan area of London.

Rome enjoys a typical Mediterranean climate that is characteristic of the Mediterranean coasts of Italy. It is at its most comfortable from April through June, and from mid-September to October; in particular, the Roman ottobrate (which can be roughly translated as the "beautiful October days") are famously known as sunny and warm days. By August, the temperature during the heat of the day often exceeds 32 °C (90 °F). Traditionally, many businesses closed during August, and Romans abandoned the city for holiday resorts. In more recent years, however, in response to growing tourism and changing work habits, the city is increasingly staying open for the whole summer. The average high temperature in December is about 13 °C (55 °F), but subzero lows are not uncommon.

Ancient Rome

One of the symbols of Rome is the Colosseum (70–80 AD), the largest amphitheatre ever built in the Roman Empire. Originally capable of seating 60,000 spectators, it was used for gladiatorial combat. A list of important monuments of ancient Rome includes the Roman Forum, the Domus Aurea, the Pantheon, Trajan's Column, Trajan's Market, the Catacombs, the Circus Maximus, the Baths of Caracalla, Castel Sant'Angelo, the Mausoleum of Augustus, the Ara Pacis, the Arch of Constantine, the Pyramid of Cestius, and the Bocca della Verità.

Medieval

Often overlooked, Rome's medieval heritage is one of the largest in Italian cities. Basilicas dating from the Paleochristian age include Santa Maria Maggiore and San Paolo Fuori le Mura (the latter largely rebuilt in the 19th century), both housing precious 4th century AD mosaics. Later notable medieval mosaic and fresco art can be also found in the churches of Santa Maria in Trastevere, Santi Quattro Coronati, and Santa Prassede. Lay buildings include a number of towers, the largest being the Torre delle Milizie and the Torre dei Conti, both next the Roman Forum, and the huge staircase leading to the basilica of Santa Maria in Ara Coeli.

Renaissance and Baroque

Rome was a major world centre of the Renaissance, second only to Florence, and was profoundly affected by the movement. The most impressive masterpiece of Renaissance architecture in Rome is the Piazza del Campidoglio by Michelangelo, along with the Palazzo Senatorio, seat of the city government. During this period, the great aristocratic families of Rome used to build opulent dwellings as the Palazzo del Quirinale (now seat of the President of the Italian Republic), the Palazzo Venezia, the Palazzo Farnese, the Palazzo Barberini, the Palazzo Chigi (now seat of the Italian Prime Minister), the Palazzo Spada, the Palazzo della Cancelleria, and the Villa Farnesina.

Rome is also famous for her huge and majestic squares (often adorned with obelisks), many of which were built in the 17th century. The principal squares are Piazza Navona, Piazza di Spagna, Campo de' Fiori, Piazza Venezia, Piazza Farnese and Piazza della Minerva. One of the most emblematic examples of Baroque art is the Fontana di Trevi by Nicola Salvi. Other notable 17th-century baroque palaces are the Palazzo Madama, now the seat of the Italian Senate and the Palazzo Montecitorio, now the seat of the Chamber of Deputies of Italy.

Neoclassicism

In 1870, Rome became the capital city of the new Kingdom of Italy. During this time, neoclassicism, a building style influenced by the architecture of antiquity, became a predominant influence in Roman architecture. During this period, many great palaces in neoclassical styles were built to host ministries, embassies, and other governing agencies. One of the best-known symbols of Roman neoclassicism is the Monument of Vittorio Emanuele II or "Altar of the Fatherland", where the Grave of the Unknown Soldier, that represents the 650,000 Italians that fell in World War I, is located.

Fascist architecture

The Fascist regime that ruled in Italy between 1922 and 1943 developed an architectural style that was characterised by its links with ancient Roman architecture. The most important Fascist site in Rome is the E.U.R district, designed in 1938 by Marcello Piacentini. It was originally conceived for the 1942 world exhibition, and was called "E.42" ("Esposizione 42"). The world exhibition, however, never took place because Italy entered the Second World War in 1940. The most representative building of the Fascist style at E.U.R. is the Palazzo della Civiltà Italiana (1938–1943), the iconic design of which has been labelled the cubic or Square Colosseum.
Galleria Borghese

After World War II, the Roman authorities found that they already had the seed of an off-centre business district of the type that other capitals were still planning (London Docklands and La Defense in Paris). Also the Palazzo della Farnesina, the current seat of Italian Foreign Ministry, was designed in 1935 in Fascist style.

Parks and gardens

Public parks and nature reserves cover a large area in Rome, and the city has one of the largest areas of green space amongst European capitals. The most notable part of this green space is represented by the large number of villas and landscaped gardens created by the Italian aristocracy. While many villas were destroyed during the building boom of the late 19th century, a great many remain. The most notable of these are Villa Borghese, Villa Ada, and Villa Doria Pamphili.

Rome has a number of regional parks of much more recent origin including the Pineto Regional Park and the Appian Way Regional Park. There are also nature reserves at Marcigliana and at Tenuta di Castelporziano.