Built during the ninth century, the Rocca Silvana was an ancient fortress owned by the abbey of San Salvatore al Monte Amiata, which later passed into the hands of the Aldobrandeschi family.
The fortress stands at the top of a hill and dominates the vast surrounding area. Its important strategic role for the control and exploitation of the nearby mines aroused the interest of the nearby city of Siena, which eventually managed to take over the fortress in the mid-fourteenth century.
Built in 1238 at the behest of Countess Tomasia, the fortress also included the parish church of San Nicola da Bari and the noble palace, built on two levels with a quadrangular plan, with the remains of a cistern for the collection and distribution of water still stands at the top. Two towers and a cistern stand next to the keep, but only a few buildings remain of the village which extended downstream of the fortress.
The church dedicated to San Nicola da Tolentino in the modern town was built at the end of the eighteenth century and modernized in 1925.
Located 1 kilometer from the Rocca Silvana, the Morone mine has existed since the time of the Etruscans for the extraction of antimony, vitriol and mercury and was exploited throughout the medieval period until modern times. The mine eventually closed in 1981 and became the property of the Municipality of Castell’Azzara after reclamation and safety work had taken place. In fact, the industrial archeology of the whole cinnabar mining process is still clearly visible, from the extraction tunnel to the processing furnaces.