Monte d'Accoddi

The original structure has a base of 27 m by 27 m and probably reached a height of 5.5 m. It culminated in a platform of about 12.5 m by 7.2 m, accessible via a ramp. No chambers or entrances to the mound have been found, leading to the presumption that it was an altar, a temple or a step pyramid. It may also have served an observational function, as its square plan is coordinated with the cardinal points of the compass.

Between 3500 and 3000 BC the remains of the original structure were completely covered with a layered mixture of earth and stone, and large blocks of limestone were applied to establish a second platform, forming a step pyramid (36 m × 29 m, about 10 m in height), reached by a second ramp, 42 m long, built over the older one. This second temple resembles Mesopotamian ziggurats and is attributed to the Sub-Ozieri period.

The site was discovered in 1954 in a field owned by the Segni family. Excavations of the Chalcolithic Abealzu-Filigosa layers indicate that it was used for animal sacrifice, with the remains of sheep, cattle and swine recovered in near equal proportions. It has been designated "the most singular cultic monument in the early Western Mediterranean". Bell Beaker pottery appears after c. 2500 BC, including hemispheric bowls, cups, tripods or tetrapods and carenated bowls, decorated in the 'pure Maritime style' and with arrangements of triangles or zigzags.

The surroundings were excavated in the 1960s and show signs of a considerable sacred center. Near the south-eastern corner of the monument is a dolmen, and across the ramp stands a considerable menhir, one of several standing stones formerly found nearby. The foundations of several small structures, possibly residential, were excavated, together with several carved stones, the most impressive being a large boulder carved into the shape of an egg and cut through on a subtle curving line.