documents about Soriano go back to the VIIIth century: the most ancient is the "Chronicon", in which are named a "Fundus Seriani" and a "Fundus Corbiani", given to the Benedictine monastery of S. Andrea in Fulmine in 747A.D. by Carlomanno; there is also a "Decreto" of the Longobard king Desiderio (773 A.D.). As reported in a letter by Leone IV (Pope from 847 till 855) and by a Papal Bull of Innocenzo III (1198-1216), in the following centuries, a part of Soriano's funds and churches became property of the diocese of Tuscania.
After the expulsion of the heretical Guastapane, in 1278 started the rule of the Orsini family. Once Orso Orsini occupated the fund and terminated the Castle, his uncle, the Pope Niccolò III choose Soriano as his summer residence. The dominion of the Orsini lasted until 1366 when Paolo Orsini, with the mediation of cardinal Egidio Albornoz, sold the castle, considered a real fortress, to the Holy See. The affair provoked the protest of the Benedictines who claimed the prperty of the castle. The dispute ended in 1373 with the bull of Gregorio XI that extabilished an allowance in favour of the monks. When it got back under the Holy See, the castle was occupied by the Breton mercenaries, called by cardinal Roberto of Geneva to soothe some rebellion. When the cardinal was elected anti-Pope (by the name of Clemente VII), the Bretons abandoned the Holy See remaining loyal to him and folowing the anti-Popes in Avignon. Only in 1420, during the pontificate of Martino V, the Bretons moved from the Castle that was given to Giordano Colonna, the Pope's brother. Until 1441, year in which it went back under the Church of Rome, Soriano was the theatre of quarrels for its possession among various mercenary captains as: Francesco Sforza and Niccolò Fortebraccio.
From this date, the village enjoyed a period of relative quietness. Thank of the interest of Pope Niccolò V Parentuccelli (1447-1455), many works of restoration of the castle started,
