Cassero Senese: A Medieval Sentinel in Grosseto

The Cassero Senese, or Sienese Keep, is a striking 14th-century fortification located in Grosseto, Italy. Built in 1344 and completed in 1345 by the Republic of Siena, it formed a crucial part of the city's defensive system. The keep was strategically positioned along the city walls, which encircled Grosseto's historic center. Standing as a robust rectangular tower, the Cassero Senese is constructed with travertine stone. Its architecture reflects its original purpose: to defend the city from external attacks and internal revolts. The keep is composed of two adjacent structures of equal height, originally serving as a watchtower and a courtyard with gates to control access to the city on the road to Siena. Remarkably, the Cassero Senese is the only architectural element of the medieval walls that was spared during the reconstruction of the city walls in the second half of the 16th century. In 1565, when Cosimo I de' Medici, the Grand Duke of Tuscany, ordered the demolition of Sienese fortifications, the Cassero Senese was saved and integrated into the Bastione Fortezza (Fortress Bastion) of the Grosseto city walls. Throughout its history, the Cassero Senese has served various purposes. In the mid-19th century, it housed the Military District until World War II. Today, after undergoing restoration, the Cassero Senese functions as an exhibition space and cultural center, hosting art and photography exhibitions. Visitors can explore its historic structure and appreciate its role in Grosseto's past.