The city wall was built during the medieval period, in defense of the thriving agricultural center. The work was completed by the Aldobrandeschi in the late thirteenth century, when Montiano had already been incorporated in the County of Sovana.In later times, the defensive structure was not changed, nor by the Sienese nor by the Medici; Only in some places it has been partly or fully incorporated from the outside walls of residential buildings.
The village was built in the late thirteenth century as a possession of the Aldobrandeschi family the County of Sovana. Its foundation was resulting in the abandonment of the castle not far from Old Montiano that, in fact, constitutes the remains. The final abandonment of the oldest castle, built between the late twelfth and early thirteenth century, it happened at the beginning of the fourteenth century as a result of a violent siege conducted by Siena, which forced the inhabitants to move to Montiano.