Le Dolmen du Couperon is a Chalcolithic (3250 - 2250BC), 8m long capstoned chamber surrounded by a ring of 18 curb stones known as a 'peristalith'. Originally covered by a long mound what remains today is largely the work of restorers. When first excavated in 1868 the capstones had fallen into the chamber. These stones, including a porthole stone were lifted and placed as capstones. In 1919 the Société Jersiaise removed the porthole stone which had been incorrectly placed as a capstone and moved it to its current position at the eastern end of the chamber. Finds included a few flint flakes and pottery fragments.
The adjacent Le Couperon Guardhouse was built in 1689 of local stone, with brick lintels. It supported a battery on the headland above as a magazine and shelter for the members of the Jersey militia that served the battery. The battery commanded Rozel Bay and by 1812 consisted of two 24-pounder muzzle-loading guns that fired over a low wall, which has long disappeared.
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.