The landscape of Volterra and Valdicecina is characterized, even from a distance, by the austere and noble lines of the fortress, wanted by the Medici not so much to protect the city and the territory, but to dominate the ancient city, deterring any revolt. The Fortress was built in 1474 - on the remains of older fortifications - exactly two years after the town was conquered by the city of Florence after a bitter war for control of the alum mines, an important mineral used in the manufacture of textiles.
The Medici Fortress consists of two military structures: the Old Fortress and the New Fortress, joined together by a double curtain surrounded by a patrol path. The Old Fortress includes parts of the older fortification made visible by recent restoration. The New Fortress consists of large stone square whose corners end in ramparts among which the “Mastio” tower stands out.
Built for military use, it was used, from the beginning, as a political prison; both opponents of the Medici and patriots of the National Risorgimento passed through its cells. Today, the “Mastio” Tower is open for visits on weekends during the summer season, while the Fortress is still a prison and therefore inaccessible to the public.