Monticchiello already in Etruscan and Roman times was the meeting place of roads linking towns and communities in the area. It still retains the features of the austere medieval fortresses, decidedly contrasting the framework offered by Renaissance Pienza.
The sturdy walls and tower of the keep which stands on the hill are the signs of the intense past of the village, a bastion of the defense system of the Republic of Siena. During the passage under the protection of Siena begins the story of Monticchiello about which, in reality, we have news that dates back to long before the city, as evidenced by the fact that his name is done go back to the Gens Roman Clelia. Since 1200 the village took its present shape with the walls, the keep and the church and were established institutions of local authorities, all provided for and regulated by statutes in the vernacular.
After the fall of the Sienese Republic in 1559 Monticchiello fell under the Medici and increasingly lost the role and the importance that it had. In 1777 it became part of the municipal jurisdiction of Pienza.
The church of Saints Leonard and Christopher still remains a witness to the heyday of the medieval fortress, preserving many of the Sienese school frescoes dating back to the fourteenth and fifteenth centuries.