From the sources it is known that in the early medieval period the curtis of Castagneto was situated in this territory and may perhaps be identified with the modern town. In the mid 8th century it was donated by the Pisan noble Valfredo to the nearby monastery of S. Pietro Monteverdi, of which he was one of the founders. The excavation revealed that its origins date back to the Hellenistic period when it may have been an outpost on the northern border of the ager Populoniensis, defending the coast and the mining district in the interior. The settlement retained its strategic importance under Roman domination, with continuous occupation between the Republican and late antique periods. The available data suggests that the summit was re-occupied between the 6th and 7th century, whilst the evidence of the 8th century wooden settlement is more certain. The latter is attested by two circular huts situated in the southern part of the borgo, the zone where the archaeological evidence was best preserved from the late medieval destruction of the summit area for the construction of aristocratic residences. In the second half of the 9th century the first stone defensive wall and a church on the summit plateau were built. A dividing wall was also built in the borgo, which in the eastern part enclosed the only point where water was available, constituted by a well, probably dating to the Hellenistic period, surrounded by wooden structures. The settlement, constituted by wooden huts, underwent alterations until the end of the 11th century, these were identified both in the area of the borgo and in the flat zones below the summit.(MiBAC)

The archaeological investigation of the castle of Donoratico, began in 2000 and has reached its ninth campaign. A settlement of great size (circa one hectare) and complexity has been uncovered, with continuous occupation between the early and late medieval period. However, the settlement’s origins date back to earlier periods between the Hellenistic era and late antiquity. The project is part of a wide ranging study being undertaken by Siena University’s Department of Archaeology, which through stratigraphic excavation and analysis of walled remains, is examining the vast territory of the lower Val di Cecina and the metalliferous territories of the Val di Cornia. The first years of excavation brought to light the castle’s layout in the late medieval period, when the fortified castle was linked to the important Della Gherardesca family, holders of numerous castles in the coastal hinterland for the control of the territory and exploitation of its resources. The layout was characterised by a summit area with buildings housing the aristocratic residence, below was the borgo arranged concentrically along the terraces and defended by a stone curtain wall. During the last three years of excavation, in particular the last campaign in 2008, interesting data emerged regarding the castle’s early medieval phases. In fact, the excavated stratigraphy attested the presence of a settlement of extraordinary importance that was unique in the regional panorama, probably linked to the early medieval monastery of S. Pietro in Palazzuolo situated close to Monteverdi Marittimo (PI). The most significant evidence dated to the 9th century when the settlement underwent numerous alterations which changed its appearance. In fact, the construction of a stone curtain wall, of an internal dividing wall within the settlement, of a single apsed church situated on the upper plateau and of a settlement built in perishable materials, attested by numerous post holes found on the summit area and in the south-western sector, all date to this century.

The tenth excavation campaign at the castle of Donoratico produced important new information to add to the substantial weight of data from the last ten years. The excavation, undertaken during June and July 2009, continued exploration of the south-western section of the settlement close to the well, one of the site’s main water sources. A stratigraphy was exposed relating to the occupation phases predating the installation of the building site for the castle’s earliest stone structures, datable to the second half of the 9th century. Of significance the traces of a circular structure built of perishable materials and sunken into the ground. Excavation also continued in an adjacent room where the remains of a large hut had been partially uncovered in preceding campaigns. Built of mixed materials and dating to the 10th century, it indicates the importance of the site in the early medieval period.