Diocese in the Province of Rome. The city in situated where the Anio, issuing from the Sabine hills, leaps down from a height of nearly 300 feet and enters the Roman Campagna. The water power of the beautiful falls, which attract many tourists to the city, is utilised in various industries and supplies the electric current that lights Rome. The slopes of the neighbouring hills are covered with olives, vineyards and gardens; the most important local industry is the manufacture of paper. The great cascade has existed only since 1835, when the Gregorian tunnel through Monte Catillo was completed, to give an outlet to the waters of the Anio sufficient to preserve the city from inundation. The "Grotto of Neptune" and the "Cascatelle" are ancient. There are ruins of two old temples, one of Hercules Saxanus, commonly called "of the Sybil", the other of Tibutus, both overlooking the great cascade. Near the Roman gate is the "Tempio della Tosse". Among the more important churches are the cathedral, the Ges(x), S. Maria Maggiore, and S. Maria degli Olivi, containing interesting fifteenth-century frescoes; also S. Maria di Quintiliolo, built on the ruins of the villa of Quintilius Varus. In the environs are many ruins of ancient villas, the largest being the famous construction of the Emperor Hadrian, which comprised a villa, portico, theatre, gardens, baths, library, etc., and covered 173 acres of ground. Many of the treasures of the Vatican Museum were discovered here. The most notable of the modern villas are the Villa d'Este (1549), and decorated with frescoes by Zuccaro; at present it belongs to the Archduke Franz Ferdinand of Austria.

According to some of the ancient writers, Tivoli was founded by the Siculi; according to others, by a colony of Argives. It is first mentioned in Roman history in 493, as included in the alliance against the Volscians, but in 361 it sided with the Gauls against Rome; though twice conquered, it shortly afterwards (339) allied itself with Praeneste (Palestrina); for some time it was in the Confederation and in the Social War became a municipium. It was strongly fortified by Belisarius in the Gothic War, but almost destroyed by Totila in A. D. 340. After the Lombard invasion it was in the power of the Byzantines and formed part of the patrimony of St. Peter. It had a count, representing the emperor. In 916 Pope John X won a memorable victory there over the Saracens. In the middle ages it rebelled at times against the popes, under Henry IV and V, and against Innocent II; at other times it fought against the Roman rebels, as under Eugene III and Adrian IV. In the thirteenth century the Senate of Rome succeeded (under Innocent IV) in imposing a tribute on the city, and arrogated to itself the right of appointing a count to govern it in conjunction with the local consuls. In the fourteenth century it sided with the Guelphs and strongly supported Urban VI against Clement VII. King Ladislaus was twice, and later Braccio da Montone once, repulsed from the city. But its strength was undermined by internal factions, in consequence of which Pius II constructed the fortress which still exists. Alexander VI withdrew it from the jurisdiction of the Roman Senate. In 1527 it was sacked by bands of the supporters of the emperor and the Colonna, important archives being destroyed during the attack. In 1547 it was again occupied by the Duke of Alba in a war against Paul IV, and in 1744 by the Austrians.

Tivoli is the birthplace of St. Severinus (sixth century), of Popes St. Simplicius and John IX, also of the painter and musician Golia. The Church of Tivoli counts many martyrs, among them St. Getulius, St. Symphorosa with her seven sons, martyred in the days of Hadrian; at a later period a basilica was erected over the place of their martyrdom. Other martyrs were Vincentius, Majorius and Generosus. The deacon St. Cletus was later confounded with the pope of that name, really St. Anacletus. The first known bishop was Candidus (465); among his successors were: Gaulterus (1000), under whom the feast of St. Lawrence, patron of the city, was instituted; Otto (1148), during whose episcopacy Eugene IV died at Tivoli; Giovanni da Gabenna O. P. (1337), who died in the odour of sanctity; Filippo de' Rufini, O. P. (1367), sent by the Romans to Gregory IX to induce him to return to Rome; Fra Lorenzo, O. M. (1450), reformer of the clergy; Cardinal Giulio Roma (1634), restorer of the cathedral and founder of the seminary; Cardinal Marcello di Santacroce (1652), who completed the work of his predecessor; Gregorio Barnaba Chiaramonti (1782), afterwards Pius VII. The diocese is immediately subject to the Holy See. In the process of concentrating the Italian seminaries the course of theology at Tivoli was suppressed. There are: 42 parishes; 40,000 inhabitants; 69 secular and 35 regular priests; 11 convents of male religious and 6 of sisters; 1 college for boys, and 1 for girls.

CAPPELLETTI, Le chiese d'Italia; VIOLA, Storia di Tivoli (Rome, 1726); BRUZZA, Regesto della chiesa di Tivoli (Rome, 1880).

U. BENIGNI