The castrum de Montecastresi stands above Camaiore in a strategic position controlling the territory and roads. The castrum is mentioned in two archive documents dated 1219 and 1231, but is perhaps to be linked back to the loco ubi dicitur Castro mentioned in a document of 950. The fortified settlement developed in an elongated form, on a north-east/south-west alignment, covering a surface area of circa 25,000 m2 and surrounded by a wall circa 1 km long. The summit was occupied by the keep, characterised to the east by a square tower and to the west by a subsidiary tower. Circa one hundred dwellings (some around the keep) and the church of S. Barbara were present on the site. In 2007-2008 an intensive survey and excavations were undertaken on the north-eastern part of the keep. The survey revealed the presence of a ditch, 9 × 5.4 m, to the south-west of the summit, on which stood an internal curtain wall on a north-east/south-west alignment. This wall surrounded the base of a quadrangular tower, of which only the imposing demolished remains were left. The survey also revealed an external curtain wall which completely enclosed the settlement’s upper part including the western tower.

The stratigraphic excavation looked at an “L” shaped area situated along the north-west and north-eastern sides of the quadrangular tower. The internal curtain wall was revealed to be a quadrangular structure of circa 11 m built around the tower, with a double access on the north-eastern side which closed a long narrow space (8 × 1,10 m). On a north-west/south-east alignment this was interpreted as the guardroom. The stratigraphy clearly showed how the curtain wall was built at the same time as the quadrangular tower. The limestone bedrock was artificially levelled and the tower’s base constructed with limestone ashlar blocks bonded with mortar. The tower, with a quadrangular base of circa 5,40 m each side, was built in a single construction phase by specialist artisans, whilst the curtain wall was built by non-specialists, or with the waste materials from the main building.

The pottery, currently being studied, and the analysis of the walls date the construction to the 12th century. The absence of housings for anchoring the wooden floors, of openings (embrasures, slits for light) and the presence of an entrance on an upper level, suggest that this was simply a watch tower. Its use would thus have been limited to the guards floor at the top, which was reached via a timber ladder, probably retractable, positioned, at least to a certain height, on the south-western side of the building. There was a cistern in the basement of the structure. The structural remains of the tower (base and rubble remains) showed signs that the building had been deliberately demolished at the beginning of the 13th century. Subsequently the area remained abandoned until the end of the 15th-beginning of the 16th century when it was converted to agricultural use through the construction of terracing for olive cultivation.

The discovery of a stretch of wall abutted by the guardroom and of early medieval artefacts including a bone pendant decorated with dice eyes, indicate early medieval occupation of the site. This will be the object of the next excavation campaign.