Tanstein Castle is one of the three castles at Dahn; the others being Altdahn and Grafendahn. Although the three castles are sited next to one another on a hill ridge, they were not built at the same time.
Tanstein is the oldest of the three castles in the group. An 1127 document refers to an Anshelmus de Tannicka as the owner or governor; as a result the castle was probably built in the early 12th century. In 1189, in a deed by Emperor Frederick Barbarossa, a Henry von der Than is mentioned and the castle designated as an immediate imperial fief. In the period that followed, Ulrich of Dahn and Conrad of Dahn are named as imperial ministeriales. In 1328 the castle became a fief of the bishops of Speyer. Until 1464 there were frequent changes of ownership, which suggests that the fief was still not inheritable during this phase, but was always re-enfeoffed.
In 1512 Frederick of Dahn purchased the castle. Because he was an ally of the knight, Franz von Sickingen, he was involved in his battles against the imperial princes in southwest Germany. After Sickingen's defeat and death in 1523, Tanstein, too, fell into the hands of the victors. Its occupation by troops of the Archbishop of Trier lasted until 1544 and probably led to irreparable damage to the structure of the castle, because it was finally abandoned in 1585. In 1689, at the start of the War of the Palatine Succession, the French completely destroyed the ruins.
Tanstein Castle is located on the two westernmost rock outcrops of the Dahn castle cluster. Both were originally linked by a bridge. On the rocks today are modern parapet walls that have been rather arbitrarily added and do not give any real idea of the old castle buildings. On the western rock outcrop there were apparently domestic-like buildings, that were built against the rocks. This is evinced by putlock holes and other marks on the rocks as well as a large cistern, in which water from the roofs was gathered and stored.
The lower ward on the southern rock outcrop still shows traces of the original walls dating to the 15th century. These include the ruins of a smithy and a smelting furnace.
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.