The castle of Buia was first mentioned in a document of 983 and was occupied until the beginning of the 15th century. What remains of the castle stands on one of the natural rises characterising the area in question. The remains comprise a sub-circular curtain wall, inside which a number of walls suggest the existence of the original partitions in the central area. It is likely that the castle was part of a larger fortified complex which developed on the surrounding high ground (hills of San Sebastiano and San Lorenzo). The territory is of great interest as it has never been systematically investigated. The only large scale excavations were those carried out in the 1980s inside the nearby church of San Lorenzo, which brought to light one of the earliest churches of Friuli, datable to between the 5th-6th centuries. Such evidence highlights the prolonged occupation of this site, distinguished by the presence of hills upon which defended structures stood that were organised into a defensive system. The presence of an early medieval castrum could also be supported by the position of the site itself, on the line of an ancient consular road that came from Concordia.

The archaeological investigations brought to light part of the north and west perimeters of the castle (respectively 180 and 100 cm wide) and a series of internal partitions belonging to rooms arranged around a central courtyard. A number of the structures were only seen in section (joins to perimeter walls) as they had been demolished following recent interventions (19th-20th century). All of the structures, built directly on the flysch bedrock, had facings of squared blocks bonded with strong lime mortar and an internal fill of rubble. The northern perimeter was seen in the collapse of its north-eastern part. In fact, the end which came to light at the western edge of the excavation was in situ, whilst at the centre and eastern end part it was completely out of alignment, probably due to an earthquake which caused it to bulge out towards the exterior. The collapse of this structure constituted one of the few in situ collapses and, has been preserved to await restoration via anastylosis, possible in this case, due to the good state of preservation of the wall’s structures. The find of a structure below the northern perimeter wall was of interest. This was a wall covered by a layer of slipped flysch, containing fragments of imbrices and a late antique coin. The presence of antique phases on the castle hill, subsequently obliterated by the early medieval complex, would seem to be compatible with the site’s history and the settlement dynamics observed in the territory in question. However, it is necessary to continue the excavation before advancing further considerations.