Le Dolmen du Mont Ubé is a Neolithic / Chalcolithic () passage grave which was discovered in 1848 by workmen quarrying for stone. The passge leads into bottle shaped chamber that used to have four internal compartments each blocked with low stone slabs. The capstones were taken as well as all but one of the internal compartments. Within the passage stand three stones that may also have had a low sill at some time. These were later used to block of the passage so it could be used as a pigsty.Finds recovered from the workmens spoil heaps included 10 or 12 pots, a Jersey bowl, vase supports, flint and stone tools, stone axes, polished stone pendants and a grape cup (unique to the Channel Islands). Burnt and unburnt human remains were noted in the cists.
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.