Follow the 'SS 70 della Consuma', turn right at 'loc. Ponticelli', continue until 'la Villa'. The ruins of the castle are a few hundred meters from the hamlet of Castel Castagnaio, on a private property.
The, really scarce, ruins of the castle, first mentioned in year 1050 as property of the Count Guidi family, are located on a 800 meters above sea-level hill that dominates the river Arno, in the high Casentino valley.
The site was inhabited since ancient times: in the year 1839, during some archeological excavations on the nearby Tramonti hill, was found the foundations of a Roman temple built on the ruins of a most ancient one.
Castel Castagnaio was a strategic stronghold of the Casentino: from here was possible to control the narrow valley of the Vincena stream that from the 'Passo della Consuma' (Consuma Pass) descend toward Florence and the ancient road coming, through Croce a Mori Pass, from the Mugello. The castle was built exclusively to play a military role and it was never seat of the land Lord. Nearby was erected a Pilgrim's hospital. Castel Castagnaio was connected 'in sight' with all other castles of the Guidi like Porciano, Stia, Papiano. After Monteaperti battle, in 1269 the castle was shaved to the ground by a Ghibelline army. In 1440, after the definitive defeat of the Guidi, the castle became possession of the Florentine Republic and its decline began.
The rest of some medieval walls are still visible. One of these two segments was the outer wall of the keep. Is still recognizable also a cistern with barrel vault. At the margin of the castle site stand the S. Bartolomeo church, built between the 16th/17th century, with material excavated from the ruins of the castle, maybe on the old castle's chapel: one of the bells of the belfry has engraved the date of 1320. Inside, below the vaults, are visible some carved corbels dating 13th century.