Blankenheim Castle was built around 1115 by Gerhard I and became the family seat of the House of Blankenheim. The lords of Blankenheim were elevated to the countship in 1380.
The site has been remodelled on numerous occasions. In the course of time the medieval defensive site was converted into a Baroque schloss with a Baroque garden and an orangery. Its end came in September 1794, when French troops marched into Blankenheim. Countess Augusta of Manderscheid-Blankenheim and her family fled to Bohemia.
For a long time the castle remained uninhabited until, in 1894, Prussia started work on safety measures. In 1926 it was taken over by the German Gymnastics Club and, in 1936, the site was acquired by the German Youth Hostel Association. They converted the castle into a youth hostel.
In 1996 the wildlife park tunnel was rediscovered. It is a noteworthy water supply gallery. Although the River Ahr flows nearby, the castle depended on rainwater. As a result, Count Dietrich III of Manderscheid-Blankenheim had a water supply tunnel excavated in 1469. The water from the spring In der Rhenn was thereby diverted from about a kilometre away and led to the castle.
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.