Just in front of the entrance to the nuraghe, about one metre away, there is a massive round building (H) with external diameter of 9 metres. Inside there is a circular room of about 6 metre diameter. It has two entrances roughly facing one another, the main one to the south and the other to the north. The former, facing the settlement, is wide and spacious; the latter, narrow and cramped, was probably a service entrance to the nuraghe. The internal wall of the room has two large niches on opposite sides; each of these has two small cabinets at 1.4 metres above the floor. The inner wall of the room also has some small niches and slits for lighting or defence. Because of the outer diameter and the slits, this building resembles the two towers of the rear antemural; moreover, some projecting blocks on the outer sides suggest that it had to be linked right to the antemural.
