The campaigns undertaken from 1999 onwards in the area surrounding the Sirai Nuraghe at Carbonia have brought to light foundations covering circa one hectare, surrounded by fortifications over 6 m wide. The structure of the fortifications was particularly evident in the north-eastern sector (Sector B), where an earthwork comprising blind spaces filled with earth and stones (end of the 7th century B.C.) was uncovered. In the north-western sector (Sector A) excavations had already revealed a pedestrian gate, (last quarter of the 7th century B.C.), oriented towards the north, and also a substantial part of the internal structure of the fortress. The latter comprised an annular quarter (insula α), built abutting the fortifications, a road (road 1), an internal insula connected to the gate structure (insula β), and an insula comprising an elliptical construction linked to other constructions with circular and elliptical plans (insula γ). The construction which seemed to have a central role in the complex was hut 2, with an elliptical plan and the entrance to the east. The first building phase, the chronology of which is still uncertain, included a structure with a circular plan (2.20 m diam.), built with squared blocks, connected to a double monolithic tank. A structure with an elliptical plan, which covered the circular building with its northern cusp, belonged to the second construction phase.

The 2008 excavations concentrated on Sector A in the fortified settlement.

North-western fortifications

The investigations provided a first definition of the tops of the walls delimiting the fortified earthwork to the west of the north gate, and a series of rooms built inside it. A tract of the pre-existing nuraghe defensive wall, on average 1.25 m wide, the surface of the earthwork’s fill comprising packed stones and soil, and a number of the broken tracts of the earthwork’s external walls were uncovered. Inside, abutting the nuraghe defensive wall, five quadrangular walls were identified (insula ε), situated between the latter and an irregular internal perimeter to the south.

Insula γ

Isolated patches of the paved surface of Road 2 (SE-NW), made up of irregular flat stones, was uncovered on a tangent to the cusp of hut 2. The road’s makeup of neatly packed small stones was also uncovered. The terminus ante quem was given by the chronology of the collapse above (second half of the 7th-full 6th century B.C.).

Inside hut 2 the removal of layer 105 (second half of the 7th-first half of the 6th century B.C.), begun in the previous campaign, was completed. The substantial deposit of collapsed mud bricks (on average 1 m deep) covered another deposit in the inner part of the perimeter of the circular building (probably a sacred fountain). This was similar in form, that is higher in the centre and sloping down towards the circular structure’s bench. In the central part of the room numerous small slabs appeared but were not sufficiently close to each other to attest that they formed a pavement. Some, found placed on edge, had clearly been in contact with fire. Destruction by fire would also explain the blackened walls in the southernmost part of the room and the appearance of a thin layer of ash spread in a uniform manner in this zone. The investigations concluded with the excavation of the deposits inside the intact double tank in the centre of the room. There was a hole between the two parts of the tank at floor level.

The evidence from the previous campaign suggested that hut 2 had a religious function, suggestion that has been fully confirmed by a careful structural comparison with the nuraghic fountain of Sedda’e Sos Carros (Oliena, prov. of Nuoro), which is of similar construction technique, size and furnishing.