Innisidgen is the site of two Bronze Age entrance graves on the island of St Mary's in the Isles of Scilly. The two burial monuments, (Upper and Lower Innisidgen) lie on a steep slope of Innisidgen Hill overlooking Crow Sound with a view towards the Eastern Isles.
The Isles of Scilly were originally settled during the Neolithic era, circa 2500 BC. Burial monuments on the islands range in date from the later Neolithic period to the Middle Bronze Age (c.2500-1000 BC). Entrance graves are distinguished by their burial chamber, typically constructed with edge-set slabs, coursed rubble walling or both, and roofed by large covering slabs. The chamber is usually accessible through an opening in the mound's stone outer edge. Excavations of entrance graves have generally uncovered cremation urns, pottery fragments and cremated and unburnt human bones.
The two entrance graves at Innisidgen Hill were built during the Bronze Age. At the time of construction, the burial chambers overlooked a coastal inlet, later known as Crow Sound. During the prehistoric era, this site would have encompassed a wide valley of fields enclosed by stone walls. The remains of a prehistoric field system are located on the northern slope of Innisidgen hill next to the entrance graves, discernible as earth and piles of rubble. No artefacts or human remains were found when both graves were first excavated in 1854.
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.