Viterbo is the main city of its own province, known as "Tuscia" or "City of the Popes", as it was the seat of the Pontifical State for 24 years, between 1257 and 1281.

The first settlements are of the Neolithic and Eneolithic Ages, whilst just a few traces evidence the passage of the Etruscans (even though it was strongly affirmed by the historians of the '400). During the Roman Empire, the Castrum Herculis was built for the presence of a temple entitled to the mythological hero.

The medieval city was edified within the fortress of the Longobardi, near the land border between Tuscia and the Byzantine dukedom of Rome.

After year 1000 the demographic growth obliged the construction of new districts outside the walls of the fortress and in 1090 the fortified walls were extended to enclose them.

From the second half of the XIII century Viterbo reached the top of its splendour as the Popes of these ages decided to choose the city as their home and seat of their conclaves.

From an architectonic point of view, Viterbo did not submit important changes until the XVI century, when the medieval town was partially rebuilt and Noble mansions and palaces appeared. Between the XVIII and XIX centuries important civic buildings were edified such as the Palazzo Apostolico (1779) and the Teatro dell'Unione (1854).

The Pope's Palace, built on the hill of San Lorenzo, a residential fortress, completed in 1266; the façade with battlements and a large staircase, features six archways with their frames in relief. To complete the perspective a large Gothic lodge.

Not to miss is the suggestive Piazza del Plebiscito, a creation of the second half of '200. Onto the square faces the Palazzo dei Priori (built in 1264 and enlarged in 1448) with an elegant portico and interior garden; the Palazzo del Governatore, il Palazzo del Podestà (with a tall Clock Tower); the antique Church of Sant'Angelo (1145) and the Old Prison. There are also a lot of buildings of the Middle Ages, Renaissance and '600 scattered around the Old City center in the districts of San Pellegrino e Pianoscarano such as:: Palazzo degli Alessandri, Palazzo dei Gatti (XII century), Palazzetto Poscia (XIV century), Palazzetto Mazzatosta, Palazzo Farnese, Palazzo del Drago (XV century), Palazzo Chigi (XVI century), Palazzo Brugiotti (XVII century), seat of the Ceramic Museum.

Fountains of great value embellish the main squares, the most important are in: Piazza della Morte (1200), Piazza Fontana Grande (1206), Piazza S. Faustino (1251), Pianoscarano (1367), Piazza della Rocca (XVI century), Piazza delle Erbe (1621), Piazza del Gesù (XVII century), Palazzo dei Priori (XVII century).
Always in Viterbo, in the district of San Martino al Cimino, worth a visit is the Abbey cistercense, the Palazzo dei Pamphili (XVII century) and the Old center built in '600 "blocks of houses", a typical example of a popular urban building plan.