Fondi is a city and comune in the province of Latina, Lazio, central Italy, halfway between Rome and Naples.
Before the construction of the highway between the latter cities in the late 1950s, Fondi had been an important settlement on the Roman Via Appia, which was the main connection from Rome to much of southern Italy.
- The Castle, with a characteristic round tower standing more than 30 meters, symbol of the city. The castle was built in the 14th century by Onorato I Caetani over a stretch of ancient Roman walls. In the 16th century it was the seat of Giulia Gonzaga's court of literates and artists. Since 1987 it houses the City's Museum.
- The adjacent Palazzo del Principe ("Prince's Palace"), constructed in 1466-1477 is attributed to the Catalan architect Matteo Forcimanya. Its portals, the bifora, the court and the loggiato forma an interesting synthesis of Catalan-Gothic and Angevine architectures.
- The Cathedral of St. Peter (Duomo, 14th century)is built over a Roman edifice identified as a temple of Jupiter. It houses the sepulchre of Cristoforo Caetani, a marble bishop cathedra and Cosmatesque pulpit from the 13th century, an Annunciation Tryptych by Cristoforo Scacco and Majesty with St. Peter and St. Paul by Antoniazzo Romano.
- The Collegiata di Santa Maria Assunta, preceded by a wide staircase and built in the 15th century by Onorato II Caetani. It has a Latin cross plant, with an aisle and two naves: main points of interests are a cyborium from 1491 and the venerated statue of the Madonna of the Sky.
- The medieval churches of San Domenico and San Francesco.