Located in the southern part of the Tuscia area of Viterbo it is famous for its mineral water. The town, which is dominated by the Borgia castle and surrounded by thick city walls, is crossed by the ancient Via Amerina that stretches from the Baccano valley to modern-day Amelia. The castle, which was reconstructed in the fifteenth century over the ruins of a previous feudal estate, has four corner keeps that differ in size and two towers, one of which is cylindrical in shape and is set up for visitors. The interior, which is currently being restored, features a large rectangular hall and two smaller halls. The cathedral of the Assunta was reconstructed in the twelfth century over a pagan temple and subsequently modified in the mid-eighteenth century. It was rebuilt again in 1831 after it was set afire by French troops. The ancient structure houses the crypt, which incorporates the ancient pagan altar with nine small aisles divided by 27 slender columns with a rich variety of capitals. The vast interior of the church, with a nave and four aisles, preserves the sarcophagus of St. Romanus by the Bernini school and a triptych with doors attributed to Paolo Romano. The sacristy has a tavola dating to the end of the fifteenth century depicting St. Romanus and St. Tolomeo.

The presbytery of the church annexed to the cemetery leads to the catacombs of St. Savinilla, over 200 meters of which are open. The niches include thousands of tombs and about thirty arched niches for sarcophaguses. Other noteworthy churches include the church of San Tolomeo (started by Sangallo the Younger and left unfinished in 1606), the church of San Eleuterio (restored in the sixteenth century), the church of San Pietro and the church of Santa Croce (dating to the year 1000, with an eighteenth-century facade). The elegant Palazzo Comunale, whose original plans drawn up by Vignola were completed much later and in a completely different style, with the contribution of Antonio da Sangallo the Younger and of other skilled workers in subsequent periods. Some of the rooms have been used for the Civic Museum, with artefacts from the many necropolises near the city: bucchero pottery and ceramics (seventh-sixth century BC), as well as Roman sculptures and stone tablets. There is also a section dedicated to the Middle Ages and the Renaissance.