The castello of Monreale is situated in southern Sardinia along the hills of the same name which dominate the Campadanese plain. The archaeological investigations were carried out in 2009 as part of a enhancement of the area. Today the castello, linked historically to the judges of Arborea, consists of a quadrangular tower on high ground which represents the central point of a fortified walled circuit surrounding the village. The walls have eight (perhaps nine) towers, both semicircular and square in plan, and two gates have so far been identified, one to the north towards Sardara and one to the west, the so-called Porta San Gavino. The tower stands at the highest point; archaeological investigation of the area have revealed a series of rooms projecting out on to a central courtyard which is divided in three sections at progressively higher ground levels.

The 2008-9 excavations season focused on the interior of the tower, while on the exterior the investigations were limited to the removal of the accumulation of earth during the 1970s behind the western side of the village. Inside the tower, the excavations of the room abutting the outer northern wall and the related underground structures continued. In room α, cleaning of the remaining archaeological deposits revealed the presence of postholes relating to a stairway leading to the upper floors. Excavations recommenced of room κ and brought to light a homogenous archaeological deposit of the 16th century, the underlying stratigraphic sequence consisted of a series of occupation levels respectively of the 15th-16th; 14th-15th, beginning of the 14th centuries. The contexts beneath the latter consist of diverse sectors. In the eastern area part of a sunken-floored wooden hut was identified, probably of early medieval date.

In Room τ the collapse of the wooden pavements of the upper floors was recovered, beneath which was a dump of rubbish probably from the nearby room Ө, dating to between the 17th and 18th centuries. The underlying stratigraphy was rich in pottery sherds of the 17th century and covered a pavement in slabs of Serrenti trachyte of the 16th to 17th centuries, similar to the paving of the entrance courtyard of the tower. In room Ө a large hearth was identified. In use over a long period, it produced the rubbish dumped in room τ, nearby. The kitchen was provided with one of the cisterns and an underground room for the conservation of foodstuffs immediately on the exterior, in the courtyard. In room δ a dump, consisting of glass and fragments of cork, included a fragment of a drinking glass with the Aragonese coat of arms of the second half of the sixteenth century. In room ε the paving systems were identified, as well as a wooden structure relating to the stairs leading to the upper floors, and the early occupation phases of the site, comprising part of a nuraghic hut filled with a rubbish dump.

The excavations also investigated rooms for the conservation and storage of foodstuffs as well as the water storage system.