It once defended the surrounding territory and it now preserves the memory of its ancient inhabitants, gradually telling the story, during the excavation campaigns, of intricate events and each time providing some pleasant surprises. From high up on a limestone elevation, the nuraghe Barru dominates the plain below, divided in half between the Municipalities of Guasila and Guamaggiore. The view from the monument extends from the two villages to the mountains of Segariu and the village of Villamar. It was built in several phases, using squared blocks of limestone marl placed in even rows. The excavation campaigns have brought to light a complex structure, made up of a central keep, facing north, and two towers positioned around a courtyard and connected by curtain walls.

The keep has an elliptical layout, typical of a proto-nuraghe, so it is likely that the central tower represents the original nucleus and that the lateral towers and the walls were built at a later time. The area so far investigated stretches for three thousand square metres, but the village may have been much larger. Along the curtain wall, you can see a system of steps and several silos, which are thought to have been used for storing agricultural products.

The nuraghe Barru is still a fascinating enigma, due to the numerous interventions - not only of extension, but also to resize the spaces -, with structural modifications, repeated design changes and renovations already carried out in ancient times, making it complicated to reconstruct its history. Adjacent to the east tower there is a small room, the use of which is still a mystery. The third tower, facing south, has a slightly smaller diameter than the other two. Inside a small room, created in the thickness of the wall, on the west side of the courtyard, there is a cistern-well, where animal and human bones, ceramic fragments and a few containers in excellent condition were found. You can access the room through an architraved entrance that opens onto the courtyard, and you will also notice a narrow staircase leading to the upper level.

The fortress took on religious functions, probably at the beginning of the Iron Age: this is shown both by the type of ceramics found in the well and the discovery of a storeroom with bronze artefacts and votive swords placed in an orderly manner and carefully sealed. To the north-east of the central body you will notice the traces of other structures, belonging to the village of huts, mostly still to be investigated. The last mystery of Barru concerns its fate: no significant quantities of materials from after the Iron Age have been found and there are no traces of destruction of the building, so the most plausible theory is that it was abandoned, for some obscure reason, and destined to be buried by sediments for thousands of years, before emerging again three thousand years later.