olmen Arghiola is a very small one; its room measures m. 1 x 2. Its uniqueness lies in being built on a slope, so that the entrance of the room is on the floor, while its back is buried. Beta Crucis, the 2nd brightest star of the Southern Cross (which, as mentioned, is no longer visible in the northern hemisphere by about three thousand years), in 2700 BC, was in front of the entrance of the structure. The orientation towards the stellar system Centaurus/ Crux / Musca is the same of many dolmens in Sardinia.