It once had a Templar function, as can be determined by the discovery within its central chamber of an altar decorated in the shape of Nuraghe, whose reproduction is in the archaeological museum dedicated to the site. The Nuragic complex Su Mulinu rises up on a small hill overlooking the valley of the Rio Mannu, less than a kilometre from Villanovafranca, the heart of eastern Marmilla. The Nuraghe complex is a juxtaposition of various construction types, from the ‘corridor’ to the tholos roof (false dome). The initial layout, consisting of blocks of marlstone, dates back to the 16th to 15th century BC (Middle Bronze I), with a village arising contemporaneously. During this period, a bastion was built with an outwork, where corridors and cells can still be seen. In the 14th century BC, a trilobed fortification and an outwork composed of four towers united by curtain walls were superimposed. On the lower floor were cells and passageway, with a number of rooms on the upper floor (the focus of excavations). In the third phase, the outwork was reinforced with a fifth tower.