Being defensible and well positioned on high ground, Monteleone Sabino was formed in the early Middle Ages when the population sought refuge in the hills to escape the Barbarian invaders.
The valley area had been inhabited since the period of the Sabines, and here lay the thriving Roman city of Trebula Mutuesca along the Via Salaria.
In the ninth century, the castle was built by the abbots of the Abbey of Farfa and a bull by Pope Martin II in 943 talked about a Leonem Montanianum. The town’s name probably depends on the presence in the area of many sculptures representating lions, including the two at the entrance of the village, or maybe for the fact that he was for a long time under the rule of Brancaleoni family of Romania.
With the crisis of the Benedictine order of Farfa some noble families since the Savelli took over, who remained there for almost 100 years, and were succeeded by the Brancaleoni.
Monteleone was sacked in 1460 by the troops of the mercenary captain Jacopo Piccinino and subsequently came under the Cesarini and, in 1480, under the Orsini. Monteleone was confiscated in 1604 by the Holy See, and in 1700 the assets of the Apostolic Chamber were entrusted to the family Gamberi-Lancelotti.