The castle of Capraia is located on a steep hill covered with woods and is already mentioned in a deed of gift made in 730 by Warnefred to the monastery of S. Eugenio. The first mention of the castle dates back to 1186, when the owners, the Ardengheschi family, were sentenced to destroy it by the royal judge Idone, at the request of Siena. The castle, however, was not destroyed and in the early thirteenth century it became part of Siena and subsequently the seat of a small village. The 20th September 1554 all the inhabitants of Capraia and the soldiers who defended it, were killed by the Florentine troops that were beleaguering Siena. The buildings remained abandoned for many years. Some of them, however, survived, including the church formerly dedicated to S. Valentino, fragments of three city walls surrounding the castle and a crenellated building with a large portal and three windows with pointed arches.