quite possibly Alpha Centauri. Types Protonuraghe Protonuraghe are considered to be the most archaic type; they differ somewhat from the "classical" (tholos vaulted) Nuraghes in their stockier look. Protonuraghes generally follow an irregular plan and lack the large circular room present in presumed later forms; instead, they are laid out along one or more corridors or long rooms. Although lacking the central circular room, they are sometimes similar sizes as later nuraghe. Mixed nuraghe This type is distinguished by the restorations made in later times, supposedly due to a change of the Protonuraghes design, or for other needs. Single tower nuraghe This is considered to be the predominant type of Nuraghe, and it represents the most diffused typology. The single tower, of a truncated conical shape, accommodates within itself one or more superimposed chambers, covered by a tholos-shaped chamber. The access, generally located at the ground level, leads into a passageway that leads, in the front, into the central chamber and in one side (usually the left) in the helical staircase, built inside the wall mass, that lead to the terrace or to the upper-floor chamber. In addition to the usual circular rooms, in their inside can be found other smaller environments such as niches. A "tancadu" nuraghe A "tancadu" Nuraghe (Sardinian term for courtyard) represents the evolution of the single tower Nuraghe; another circular building was later added to the main tower, with two enclosing curtain walls connecting the two. A courtyard was present within the structure, sometimes provided with a well. Polylobed nuraghe Also called Nuragic royal palaces, the polylobed Nuraghes are the least frequent typology. Very elaborate and often designed in a unified manner, they look like veritable fortresses with several towers linked by high ramparts, whose function was to offer more useful space and perhaps to reinforce the central tower. These "Megalithic castles" were surrounded by additional walls, sometimes also provided with towers (the so-called bulwark). Notable nuraghes Nuraghes are inscribed on the UNESCO World Heritage Site list. Su Nuraxi di Barumini, in the south of the island, has been chosen to represent all the nuragic patrimony, but one of the highest and most complex Nuraghes is the Nuraghe Santu Antine near the village of Torralba, in northern Sardinia. Other famous nuraghes are near Alghero (Nuraghe Palmavera), Macomer, Abbasanta (see Losa), Orroli (Nuraghe Arrubiu), Gonnesa (Nuraghe Seruci) and Villanovaforru (Nuraghe Genna Maria). Date and cultural significance