The archaeological area is located on a marble-limestone ridge that dominates the course of the Mannu River, in the eastern Marmilla, in the central-southern part of the island.
The nuraghe, which has returned an extraordinary nuragic altar, is built with marl blocks. The entire floor plan is not yet known, but three construction phases have been identified.
The first phase, perhaps of Middle Bronze I (16th-15th century BC), saw the installation of a bastion and an antemural with corridors and cells with a stepped pointed opening.
In the second phase, of Middle Bronze II (14th century BC), a three-lobed, sinusoidal bastion was superimposed on the building, which housed numerous cells and short andites on the lower floor. Among the rooms on the upper floor, the sub-triangular “compartment Bs” (3.60 m x 3.20 m), dates back to Middle Bronze (15th-14th century BC). A new antemural of four towers was also built, joined by irregularly straight curtains.
In the third phase, the antemural was equipped with another tower (F) and curtains. The tower F (eastern diameter 9.30 m; int diameter 5.60 m) has 11 louvers, 2 raised rectangular windows and entrances to the lower compartment F1 and the corridor Ci5. On the right of the access corridor, sub-trapezoidal (m 1.80 x m 4.50 h), there is a staircase that leads to room F2, above room F1; on the left there is an entrance to room F3. The tower was reused for civil and funerary purposes in the late Punic, Roman and early medieval ages.
The F1 compartment, irregularly pentagonal, with a lowered “tholos” vault, rests partially on the underlying Ci5 corridor of the first external wall. The upper layers have returned late-Punic, Roman-Republican finds and a few fragments of late Bronze-early Iron Age. Recent bronze finds come from the lower layer of ash and charcoal, which rested on the pavement of the room.
The room F2, similar in plan to the room F1, has returned early medieval materials.
The room F3, subrectangular (m 6 x 2.35-1.10), has a niche in the corner N and, on the O side, the entrance to the stairwell that leads to the room F4 above. Below the early medieval, Roman, late Punic and Roman-republican levels, a layer has been found resting on a clay-framed slab floor that has, in the N corner, a hearth with ashes, charcoal and finds from late Bronze-early Iron Age; perhaps perfumed substances were burned there. A second floor is coeval with the construction of the room, which took place in late Middle Bronze-early recent Bronze.
Room E - located on the lower level of the second-phase bastion - was used as a place of worship starting from the 14th century BC, as witnessed by two ritual hearths. The rites, perhaps suspended between the 13th and 11th centuries BC, resumed between the end of the 9th and 9th centuries BC. At this age, a seat counter and an extraordinary monumental sandstone altar in the shape of a nuraghe, located in the NE corner, date back to this age.
The altar has a basin on the top intended for collecting liquids which, through a channel, flowed into a tank. It was decorated with four else (three remnants) of sculpted swords supporting bronze blades. Other bronze objects, perhaps long stalks with anthropomorphic and animalistic figurines, decorated the altar above, presumably representing the myth underlying the cult. Under the crowning of terrace shelves, a crescent moon is sculpted.
Interrupted between the end of the 6th century BC and the 4th century BC, the cult resumed in Roman times, with maximum intensity between about 50 BC and 150 AD. The upper part of the altar was then replaced with a stone and mortar wall.
From Middle Bronze to ancient orientalizing, a vast village developed around the nuraghe. Occasionally frequented (VII-VI century BC), abandoned (V-IV century BC) and reoccupied (late IV-III century BC), it lasted until the early Middle Ages, as attested by the remains of complex buildings and numerous finds.

History of excavations
The complex has been excavated several times, starting in 1983, by Giovanni Ugas.

Bibliography
G. Ugas, “A new contribution to the study of tholos in Sardinia. The fortress of Su Mulinu-Villanovafranca”, in Nuragic Sardinia and the mycenean world, 3, edited by M. S. Balmuth, Oxford, BAR, 1987, pp. 77-128;
G. Ugas, “The chapel of the vain and in the nuragic fortress of Su Mulinu-Villanovanca (CA)”, in Ancient Sciences. History, Archaeology, Anthropology, 3-4, 1989-90, pp. 351-373; G. Ugas-M.C.
Paderi, “Ritual and cultural persistences of the Punic and Roman ages in the Nuragic chapel of the cave and the fortress of Su Mulinu- Villanovafranca (CA)”, in Roman Africa. Proceedings of the III study conference (Sassari, 15-17 December 1989), Sassari, 1990, pp. 475-479.