Tivoli (/ˈtɪvəli/ TIV-ə-lee; Italian: [ˈtiːvoli]; Latin: Tibur) is a town and comune in Lazio, central Italy, 30 kilometres (19 miles) north-east of Rome, at the falls of the Aniene river where it issues from the Sabine Hills.

Gaius Julius Solinus cites Cato the Elder's lost Origines for the story that the city of Tibur was founded by Catillus the Arcadian, a son of Amphiaraus, who came there having escaped the slaughter at Thebes, Greece.

From the tenth century onwards, Tivoli, as an independent commune governed by its elected consuls, was the fiercest rival of Rome in the struggle for the control over the impoverished central Lazio.

Tivoli however managed to keep a level of independence until the 15th century: symbols of the city's strength were the Palace of Arengo, the Torre del Comune and the church of St. Michael, all built in this period, as well as the new line of walls (authorized in 1155), needed to house the increasing population.

In the 13th century Rome imposed a tribute on the city, and gave itself the right to appoint a count to govern it in conjunction with the local consuls.

In the fourteenth century, Tivoli sided with the Guelphs and strongly supported Urban VI against Antipope Clement VII.

In 1461 Pope Pius II built the massive Rocca Pia to control the always restive population, and as a symbol of the permanence of papal temporal power here.

The most famous of these is the Villa d'Este, a World Heritage Site, whose construction was started in 1550 by Pirro Ligorio for Cardinal Ippolito II d'Este and which was richly decorated with an ambitious program of frescoes by painters of late Roman Mannerism, such Girolamo Muziano, Livio Agresti (a member of the "Forlì painting school") or Federico Zuccari.

The "Great Waterfall" was created through a tunnel in the Monte Catillo, to give an outlet to the waters of the Aniene sufficient to preserve the city from inundations like the devastating flood of 1826.

Tivoli., a poem by Letitia Elizabeth Landon published in The Bijou annual for 1829 to accompany an engraving of 'The Cascade of Tivoli', a painting by Henning.