The exact building date of Castel Gavone ('Castrum Govonis'), the former seat of the Del Carretto Marquisses, is still unknown. The castle rises on a huge, steep curvilinear rampart on top of the Becchignolo hill.
The castle was allegedly built by Enrico II in 1181 on remains of previous defensive structures. It was certainly fortified in 1292. Destroyed during the struggles with Genoa, it was rebuilt by Giovanni I in 1451-1452, along with the Borgo walls.
It underwent further modifications until 1715 when it was largely dismantled by the Genoese who wanted to destroy the symbol of their ancient enemy after their conquest of the Marquisate. Only some of the retaining side-walls were spared in addition to the very famous Diamond Tower (today the best-preserved structure). The Tower, which has a curved triangular base, was built using diamond-faceted squared stones. It faces south with its acute edge resembling the bow of a ship. It is an excellent example of late medieval military architecture. Many of the original materials such as beams, stones and columns, were later used to build churches, gates and houses.References:
Monte d"Accoddi is a Neolithic archaeological site in northern Sardinia, located in the territory of Sassari. The site consists of a massive raised stone platform thought to have been an altar. It was constructed by the Ozieri culture or earlier, with the oldest parts dated to around 4,000–3,650 BC.
The site was discovered in 1954 in a field owned by the Segni family. No chambers or entrances to the mound have been found, leading to the presumption it was an altar, a temple or a step pyramid. It may have also served an observational function, as its square plan is coordinated with the cardinal points of the compass.
The initial Ozieri structure was abandoned or destroyed around 3000 BC, with traces of fire found in the archeological evidence. Around 2800 BC the remains of the original structure were completely covered with a layered mixture of earth and stone, and large blocks of limestone were then applied to establish a second platform, truncated by a step pyramid (36 m × 29 m, about 10 m in height), accessible by means of a second ramp, 42 m long, built over the older one. This second temple resembles contemporary Mesopotamian ziggurats, and is attributed to the Abealzu-Filigosa culture.
Archeological excavations from the chalcolithic Abealzu-Filigosa layers indicate the Monte d"Accoddi was used for animal sacrifice, with the remains of sheep, cattle, and swine recovered in near equal proportions. It is among the earliest known sacrificial sites in Western Europe.
The site appears to have been abandoned again around 1800 BC, at the onset of the Nuragic age.
The monument was partially reconstructed during the 1980s. It is open to the public and accessible by the old route of SS131 highway, near the hamlet of Ottava. It is 14,9 km from Sassari and 45 km from Alghero. There is no public transportation to the site. The opening times vary throughout the year.