According to known historical reports, the Castle of Valentano was originally founded, as a defensive structure, around 1053. Some claim that a wall enclosed with a strong tower, the church dedicated to St. John and the first houses.
The war between Orvieto and Viterbo led to a series of destructions and reconstructions of the castle up to the fire, in 1252, that partly burned the town saved, according to tradition, from Sant’Agata, the protector against fire.
The Castle of Valentano, starting from the octagonal tower, was rebuilt in 1296 on pre-existing medieval defensive buildings.
In 1327, under Louis of Bavaria, the country and the walls of Valentano suffered severe damage and more damage was caused by the troops of the prefect Giovanni Di Vico of Viterbo in 1350.
Years of peace for our Castle began with the arrival of the Farnese family, who took possession of the castle in 1354, at the time of Cardinal Albornoz, during the presence of the Popes in Avignon. Subsequently the Farnese became masters of Valentano and other neighboring centers.
The Castle was inhabited by the Farnese family in a more frequently in 1400 when it a part of the monument was renovated and the Round Tower built in the eastern part. Still other work was done towards the end of 1400 creating the “courtyard of love” for the marriage of Angelo, the son of Pier Luigi the Elder and Lella Orsini of Pitigliano, celebrated in 1488. The magnificent capitals are the work of a certain Lorenzo, stonemason of Florence. The backyard speaks of this marriage through the union of coats of arms of the two families and the allegory of blooming farnesian lilies that appear on the capitals of the lower columns.
Later, other changes took place at the time of the marriage of Pier Luigi Farnese, junior, with Gerolama Orsini in 1519, with contributions by Antonio da Sangallo the Younger (as it appears in the travertine parapet well placed to one side instead of the courtyard, some elements such as portals, jambs of windows and, above all, in the monumental fireplace located in the upper “Sala Ducale”). These were the best years of life of the castle that saw the birth of important personalities, such as: Alessandro and Ranuccio, future cardinals, the Dukes Ottavio and Horace and Victoria, Duchess of Urbino.
In 1534, Alessandro Farnese was elected Pope under the name of Paul III. He wanted to build the grand lodge, with the eleven tuff and brick arches oriented to the west, still called Loggia of Paul III.
Pier Luigi, in 1537, became Duke of Castro and, in 1545, Duke of Parma and Piacenza.
The castle was still inhabited by the Duchess Gerolama Orsini and his son Cardinal Alessandro Farnese, who built a large frescoed staircase to go up to their apartments.
The Farnese family were forced to leave the Castle Valentano in 1649, after the war with the state of the Church and the destruction of Castro, capital of the Duchy.
The monument was first used as a granary and prisons of the Community and, therefore, used from 1731 to the Monastery of Dominican Sisters who transformed the castle into several parts and, above all, built a staircase in the ancient Holy Stairs of Alessandro Farnese.
During the Risorgimento wing of the castle housed a garrison of Zouaves, French soldiers sent to Valentano by Pius IX to fight Garibaldi (1867-1870).
When, in 1930, the nuns of the Monastery were transferred to Gubbio, the castle was destined to house the elementary schools and then some parts were used as dwellings.
The castle, abandoned in 1957, was restored in 1979.
Today it houses the Town Library (since 1989) and the Museum of Prehistory of Tuscia, opened in 1996.