The Callanish Stones are an arrangement of standing stones placed in a cruciform pattern with a central stone circle. They were erected in the late Neolithic era, and were a focus for ritual activity during the Bronze Age. Archaeological excavation in the 1980s proved that the main circle was erected 4,500-5,000 years ago, and the chambered tomb a few generations later. The setting has a unique arrangement, with lines of stones radiating in four directions from the ring. It is not fully clear whether the stone alignments were constructed at the same time as the ring, or later. The layout of the site, along with many others across the British Isles, appears to have an association with astronomical events, the precise nature of which cannot be determined.
Numerous other ritual sites lie within a few kilometres. These are mainly more modest rings of standing stones, or single monoliths. The most impressive Cnoc Ceann a' Ghàrraidh and Cnoc Fhillibhir Bheag lie just over a kilometre south-east of the main Calanais ring, and originally consisted of rings of stones at least eight in number.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.