erection Forte Sangallo wanted by Pope Alexander VI Borgia , and entrusted to the architect Antonio da Sangallo the old man from 1494-95 revolutionized the internal urban structure Civita Castellana. The most important consequence was represented by the abandonment of the Piazza del Duomo and the establishment of the new pole in the square of Prato who also became the town square with the construction of the municipal building. The history of the Renaissance period, there are evidenced by a local news entitled of the history of Civita Castellana Francesco Pechinoli who wrote around 1560;
the story, divided into two parts gives us information on people who held the roles of governor of the city : Alexander VI Borgia (1492-1503), immediately after his ascension to the papal throne, gave Cesare Borgia, known as Valentine, the perpetual government of the city.
The death of Pope Alexander VI in the summer of 1503 also marked the decline of her son, who sent troops to occupy Nepi and Civita Castellana: nell'Istoria it tells how the people resisted the attempts of the Count Oliva, made by Valentino, not allowing to conquer the fortress.
In 1513, for the munificence of Leo X (1513-1521) was built Town Hall, stood as an 'inscription in front of the building: Leonis X Pont. MAXIM. IN VEIO LIBERALITATE. He gave the city government to Dovizi by Bernardo Bibiena.
Giulio de 'Medici, ruler of the city, became pope under the name of Clement VII (1523-34), left the government at the same Cardinal Giovanni Salviati, who remained until the death of the pontiff. During this period, Civita Castellana is involved in the events of the Sack of Rome having to fight against the troops of mercenaries, who had obtained a permit from the Pope to hand over the city and the fortress.
the death of his successor, Clement VII, Paul III Farnese (1534-1549), appointed governor of the city's nephew Alessandro Farnese :"... special grace of the supreme God, kind to get for governor, even rather than as father and protector for the nephew of Paul de 30 years. "
Under the pontificate of Julius III del Monte (1550-1555) the city had a strong hunger for the lack of grain. The pontiff "to please Balduino Mount his brother, Cardinal Farnese removed, giving the city and the regency Rocco fortress of Monte Galletti, who chose as his collaborator's brother Domenico. The pontiff later
Paul IV Carafa (1555-59), appointed governor "as usual" Cardinal Carlo Carafa, August 13, 1555.
A 'exception to the rule was the appointment of Mario Ark on 12 March 1559, it acquired in Civita Castellana temporary government for a short period and was subsequently replaced, the election of Pius IV (1560-65) with Carlo Borromeo.
Following the election of Gregory XIII was entrusted with the government to Filippo Boncompagni 25 July 1577 and in second term April 3, 1581.
On the eve of the papal election Felice Peretti the government of Civita Castellana was still held by Cardinal Boncompagni as reflected in the acts of 1586. Even Sisto V continues in practice to entrust the government of the city to its cardinal nephew, we find confirmation in the notarial documents preserved at the State Archives of Viterbo. On the death of Sixtus V, Clement VIII Aldobrandini appoints the cardinal-nephew Peter , governor of the city.