(anc. Tibur), a celebrated town of the Papal States, in the Comarca, and 18 miles N. by E. of Rome. It stands on the slope of Monte Ripoli, on the left bank of the Teverone (anc. Anio), just at the point where it descends by a series of rapids to the plain of Rome. It is now a dirty, disagreeable place, with wretched houses, and narrow, steep, unpaved streets. It has a cathedral and several other churches, some of them very old; but its chief interest is derived from the beautiful scenery, the falls of the Teverone, and the remains of ancient buildings in the town. The appearance of the falls has been much altered by an inundation, which, in 1826, swept away a number of buildings, and rendered it necessary to alter the channel of the river. It now falls in one mass to a depth of 80 feet; and there are also several smaller cascades. The antiquities of Tivoli are numerous; but the names and even the character of most of them are very differently described by different antiquaries. What is commonly called the Temple of Vesta, an elegant circular building overhanging the river, is identified by some with that of the Sibyl, and by others with that of Drusilla; and the extensive ruins generally known as the villa of Marcenas are said by some to be a temple of Hercules, and are now occupied by an iron-work established by Lucien Bonaparte. Tibur was a very ancient town, and is said to have been founded, long before Rome itself, by three brothers, named Tiburtus, Coras, and Catillus, grandsons of Amphiarus, who flourished in Greece long before the Trojan war. No important events are recorded in its ancient history, which is chiefly occupied with the various feuds and wars carried on with Rome, under the power of which it eventually fell. In the time of Augustus it was a favourite summer retreat of the Romans, and even of that emperor himself. Many of the principal men of the day are known to have had villas here; and the poets Horace, Catullus, and Propertius, have celebrated the beauty and pleasantness of the place. Catullus had an estate in the vicinity; but it is doubtful whether Horace had a villa here or not, although he lived much at Tibur. In later times it was the residence of Zenobia, the captive queen of Palmyra, in the last years of her life. In the middle ages, Tivoli was an imperial city, independent of Rome, and was the occasion of many contentions between the emperors and the popes; in the course of which it was frequently taken and retaken as either party gained the ascendant. Pop. 6200.