The Piagnaro Castle is a medieval building that has been restructured several times over the years. To the north, there is the keep of the fortress, which is flanked by a bastion from the Medicean era. At the centre is the oldest part of the complex and it was likely built in the first half of the 1200s. To the south, the residence of military leaders has a 17th-century style. Beginning at the end of the 1600s, the fortress was used mainly as a police station. In the 1900s, it was used as an elementary school. It was restored in 1957-8 and became the home of the museum.