Trematon Castle was the caput of the feudal barony of Trematon. It overlooks Plymouth Sound and was built probably by Robert, Count of Mortain on the ruins of an earlier Roman fort: it is a motte-and-bailey castle and dates from soon after the Norman conquest.
Trematon Castle, like Restormel Castle, has a stone shell keep raised on an earlier motte. Although in ruins, much of the Norman walls remain standing, so that the original form of the Castle and keep are clear. The internal diameter is approximately 21 metres. A rectangular gatehouse, built in 1270, has two floors and a portcullis. Both are in good condition. The castle is currently open to the public.
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.