A 360° view from the fortress overlooks most of Tuscany. The current appearance is the result of multiple renovations made over the centuries, to adapt the original stronghold (11th and 12th centuries) to the evolution of military technology, culminating with the introduction of firearms in the 15th century. In that period the imposing polygonal perimeter walls, with corner turrets, were built. Around the fortress, there is a fortified village, whose walls still show the remains of the two main entrances: Porta Volterrana and Porta San Rocco, with numerous remains of houses near Porta San Rocco. Inside the fortress is a mighty guard tower and three large buildings leaning on the walls that overlook a courtyard. To the left of the entrance, the square tower assimilated into the building to the north (A) stands, this is the oldest building coming from the original medieval stronghold (11th-12th century). Access to the tower was through a door located on the south side but there is no longer trace of the flight of steps. Inside angular stone corbels supported the wooden floors. The excavation carried out by the Archaeological Superintendence inside the Tower in the 1980s has unearthed pottery, arrowheads, fragments of glass and a sword, now displayed in a hall of the Mostra Permanente Guerrieri e Artigiani in Pomarance.
History in short: The hamlet of Sillano dates back to Etruscan times, as witnessed by various archaeological finds. The settlement of Sillano was first mentioned in a document from the 10th century written by the bishop of Volterra, and the fortified settlement in 1067 in a document recording the sale of lands. Probably the guard tower – now inserted into the structure of the fortress – dates back to this period. Over the centuries, the Sillano stronghold underwent several changes of ownership. In 1406 the fortress passed under Florence. In the 16th century the period of decline began. In the 1980s, the fortress was donated to the Town hall of Pomarance.