Cassero Senese

The Cassero Senese (English: Sienese Keep) is a 14th-century fortification located in Grosseto, Tuscany, Italy.

Built by the Republic of Siena, it survived the demolition of the Sienese fortifications ordered by Cosimo I de' Medici, Grand Duke of Tuscany in 1565 and was incorporated in the Bastione Fortezza (Fortress Bastion) of the Grosseto city walls.