Their peculiar shape gives an anthropomorphic appearance to the rock, almost as if it were watching over the extraordinary testimonies of the remote past with a severe countenance. The four domus de Janas of the Filigosa necropolis rise at the foot and on the slopes of a hill topped by the imposing tower - 13 meters in diameter - of the Ruiu nuraghe. The pre-nuragic burial ground is a few kilometres from Macomer, the main centre of the Marghine, and is closely linked to that of Abealzu, in the territory of Osilo. Although they are 60 kilometres apart, the two sites, Macomerese and Osilese, have architectural similarities, in terms of type of burials and identical finds: from the two necropolis derives the name of an important cultural facies of the Sardinian Eneolithic, the culture of Abealzu - Filigosa - also known only as Filigosa -, developed between 2700 and 2400 BC

Four tombs have been investigated so far: three dug into the tufa at the foot of the hill, and the fourth to a higher level, although the original the number of burials had to be much higher.