Since the 10th century the history of the Fumone Castle is strongly tied to that of the church.
The impregnable fortress of Fumone was used by the popes for over 500 years as defensive citadel and as prison for political enemies.
The most renowned episode that took place in the Castle of Fumone is in 1295 and has as main character Pope Celestino V  who, after ten months of harsh imprisonment, died here.
The time in office of pope Celestino V lasted only a few months, in fact his pure soul soon entered into a conflict of conscience with the political decisions that often had to be made in the interest of the church, and after a hard distress he abdicated. Pope Boniface VIII was elected in his place. The new pope once realized the illegitimacy of his election, decided to imprison Celestino V in a pontifical prison of maximum security. Just after his death, at the Fumone Castle, Celestino V did his first miracle. Since then the castle, which had always had a military nature, became a place spiritual importance.
During the XVI century when the castle of Fumone more and more lost its military role, the castle started its decline. Therefore, in 1584 Pope Sixtus V decided that, having died here Celestino V, the castle was to be preserved as historical memory, and entrusted it to the Marchesi Longhi family, which have preserved it and enhanced it over the centuries.