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 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 joins the Tiber north of the historic centre.
Although the city center is about 24 kilometres (15 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 metres (43 ft) above sea level (at the base of the Pantheon) to 139 metres (456 ft) above sea level (the peak of Monte Mario). The Commune of Rome covers an overall area of about 1,285 square kilometres (496 sq mi), including many green areas.