FONDI (anc. Fundi), a town of Campania, Italy, in the province of Caserta, 12 m. N.W. of Formia, and 11 m. E.N.E. of Terracina by road. Pop. (1901) 9930. It lies 25 ft. above sea-level, at the N. end of a plain surrounded by mountains, which extend to the sea. It occupies the site of the ancient Fundi, a Volscian town, belonging later to Latium adjectum, on the Via Appia, still represented by the modern high-road which passes through the centre of the town. It is rectangular in plan, and portions of its walls, partly in fine polygonal work and partly in opus incertum, are preserved. Both plan and walls date, no doubt, from the Roman period. The gate on the north-east still exists, and bears the inscription of three aediles who erected the gate, the towers and the wall. A similar inscription of three different aediles from the N.W. gate still exists, but not in situ. In the neighbourhood are the remains of several ancient villas, and along the Via Appia still stands an ancient wall of opus reticulatum, with an inscription, in large letters, of one Varronianus, the letters being at intervals of 25 ft. The engineering of the ancient Via Appia between Fondi and Formia, where it passes through the mountains near Itri, is remarkable.
The modern town is still enclosed by the ancient walls. The castle on the S.E. side has some 15th-century windows with beautiful tracery. Close by is the Gothic church of S. Pietro (formerly S. Maria), which was the cathedral until the see was suppressed in 1818 and united with that of Gaeta; it contains a fine pulpit with "cosmatesque" work and the fine tomb of Cristoforo Caetani (1439), two interesting 15th-century triptychs and an episcopal throne, which served for the coronation of the anti-pope Clement VII. in 1378. In the Dominican monastery the cell which St Thomas Aquinas sometimes occupied is shown.
The ancient city of Fundi in 338 B.C. (or 332) received (with Formiae) the civitas sine suffragio, because it had always secured the Romans safe passage through its territory; the people as a whole did not join Privernum in its war against Rome three years later, though Vitruvius Vacca, the leader, was a native of Fundi. It acquired the full citizenship in 188 B.C., and was partly under the control of a praefectus. The inscription upon some waterpipes which have been discovered shows that later it became a municipium. It was governed by three aediles: Horace's jest against the officious praetor (sic) is due to the exigencies of metre (Th. Mommsen in Hermes, xiii. p. 113). The family of Livia, the consort of Augustus, belonged to Fundi. During the Lombard invasions in 592 Fundi was temporarily abandoned, but it seems to have come under the rule of the papacy by A.D. 754 at any rate. Pope John VIII. ceded it with its territory to Docibile, duke of Gaeta, but its history is somewhat intricate after this period. Sometimes it appears as an independent countship, though held by members of the Caetani family, who about 1297 returned to it. In 1504 it was given to Prospero Colonna. In 1534 Khair-ed-Din Barbarossa tried to carry off Giulia Gonzaga, countess of Fondi, and sacked the city. After this Fondi was much neglected; in 1721 it was sold to the Di Sangro family, in which it still remains. Its position as a frontier town between the papal states and the kingdom of Naples, just in the territory of the latter - the Via Appia can easily be blocked either N.W. at the actual frontier called Portella  or S.E. of it - affected it a good deal during the French Revolution and the events which led up to the unification of Italy.
The Lago di Fondi, which lies in the middle of the plain, and the partially drained marshes surrounding it, compelled the ancient Via Appia, followed by the modern road, to make a considerable détour. The lake was also known in classical times ass, lacus Amyclanu from the town of Amyclae or Amunclae, which was founded, according to legend, by Spartan colonists, and probably destroyed by the Oscans in the 5th century B.C. (E. Pais in Rendiconti dei Lincei, 1906, 611 seq.); the bay was also known as mare Amunclanum.
The ancient Speluncae (mod. Sperlonga) on the coast also belonged to the territory of Fundi. Here was the imperial villa in which Sejanus saved the life of Tiberius, who was almost crushed by a fall of rock. Considerable remains of it, and of the caves from which it took its name, still exist 1 m. S.E. of the modern village. For modern discoveries see P. di Tucci in Notizie degli scavi (1880), 480; G. Patroni, ibid. (1898), 493. The wine of Fundi is spoken of by ancient writers, though the ager Caecubus, the coast plain round the Lago di Fundi, was even more renowned, and Horace frequently praises its wine; and though Pliny the Elder speaks as if its production had almost entirely ceased in his day (attributing this to neglect, but even more to the excavation works of Nero's projected canal from the lacus Avernus to Ostia), Martial mentions it often, and it is spoken of in the inscription of a wine-dealer of the time of Hadrian, together with Falernian and Setian wines (Corpus inscript. Lat. vi. Berlin, 1882, 9797). The plain of Fondi is the northernmost point in Italy where the cultivation of oranges and lemons is regularly carried on in modern times.
See G. Conte Colino, Storia di Fondi (Naples, 1902); B. Amante and R. Bianchi, Memorie storiche e statutarie di Fondi in Campania (Rome, 1903); T. Ashby, in English Historical Review, xix. (1904) 557 seq.
 For the pass of Ad Lautulas see Terracina.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)