To the visitor who coming from the plain of Romagna, the city-fortress of San Leo appears with its high polished shield of rock. The first Fort was built by the Romans. In the Middle Ages was bitterly fought over by the Byzantines, Goths, Franks and Lombards. In 1441, the young Federico da Montefeltro was the author of an enterprising climbing. With the new ownership of the Della Rovere, the use of the building changed from Fortress to prison, whose cells were obtained in the accommodation of the military. Among the inmates who were imprisoned names such as Felice Orsini and adventurer Cagliostro from Palermo. The Fortress consists of two distinct parts: the rock, with its square turrets and Gothic entrance, is the most ancient part; and the residential wing, with round towers and a massive wall hull with corbels, the most recent invoice.