Many people think of Viterbo as the city of popes and the Middle Ages. For them it is of little importance if just outside the castle walls, amidst ruins and tunnels dug out of the tuff, there are still signs of ancient and rudimentary burial grounds belonging to the pre-Roman village, or if, not far off (Ferento, Aquae Passeris), buildings of the Augustan age are still standing.

The tourist's image of Viterbo is the one borne out by the districts of San Pellegrino and Pianoscarano, by the many fountains, by the walls and the papal palace on the Colle del Duomo opposite the cathedral, aristocratic evidence of the finest years in the city's history, when for much of the thirteenth century the Vetus Urbs gave hospitality, together with other cities of the Patrimony of St. Peter, to popes and cardinals for shorter or longer periods of time. In particular, Viterbo, an ideal and inviting city thanks to its fresh air and especially because it was solidly walled in, provided a salutary refuge for Innocent III, Gregory IX, Alexander IV, Clement IV, Hadrian V and other popes. The French pope, Clement IV, was to go into the history books for having caused the longest period a Papal see has ever been vacant, following his death in Viterbo in 1268. In fact, it took almost three years before the white smoke was seen, marking the election of Gregory X in 1271.

Among the other popes elected in Viterbo we should remember the "Hispanic Peter", John XXI (the only Portuguese pope in the history of the church, who died in Viterbo in 1276), a doctor and scientist whose funeral monument can be admired in the cathedral.

The cathedral will be the starting point for our tour of the city, which can be comfortably undertaken on foot. We recommend you leave your car in one of the car parks outside the historic centre and enter by one of the gates in the boundary walls: some are bare (Carmine, Fiorita, San Pietro, Murata), while others opulent with ashlar-work and trappings (Romana, Verità, Fiorentina). One of these (Faul) still preserves a sturdy little tower over the architrave, a residue of the last renovation in the seventeenth century. All that remains of another gate (Sonsa) is a marble inscription, in Romanesque-Gothic, dated 1095.