Conrad I, Count of Vintimiglia, built the castle in Roquebrune-Cap-Martin in 970 to defend the Western border of his feudal domain from attack by hordes of Saracens that rampaged around the area. Initially the entire village was encompassed by the castle. The keep's military strength was reinforced in the 15th century by the Grimaldi family. In 1808 the castle was sold as a Bien National to five Roquebrune inhabitants. A century later, in 1911, it was sold again – this time to wealthy Englishman Sir William Ingram, who set about renovating it but eventually gave it to the town of Roquebrune in 1921. The castle overlooks the medieval village and its atmospheric alleyways, sometimes carved out of the rock itself.
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.