The works for the construction of this fortress started in 1494. It was designed according to the military standards of the era, when the advent of artillery was substantially changing the appearance of all defensive structures. The fortress, called "Borgia's" in honor of Pope Alexander VI, was completed in 1500 and different artisans alternated during its construction. The first castle was the one of Giovanni I Olivieri from Foligno, who was obliged to reside permanently in the castle together with the whole garrison. Later, Giovanni's descendants acquired the estate of Frecco (in Valfabbrica). The municipality of Perugia always opposed the building of defensive structures, so much to send a military contingent led by Orsini for lowering it. However, the assaults were vain, both for the validity of the structure, designed to withstand independently a long siege, and for the courage of the commander Crispoldi of Foligno. In 1624 the castle was home to Galileo Galilei, who stayed there for a few days. In the second half of 1600, the military building underwent a steady decline that led to require, in 1965, adequate restoration at the expense of the municipality of Foligno. In 1877 the building was still in a serious decay status: some of the brackets had collapsed and they were restored in 1955. The fortress has the shape of an equilateral triangle in which each vertex corresponds to a round tower and to a truncated cone that communicates with the other ones through underground walkways. The tallest tower has an 80 meters circumference base, it is 20 meters high and it dominates the village. It consists of 5 floors where all the elements necessary for the defense and for the inhabitants of the garrison are still visible.