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:The first written record of church in Danmark locality date back to the year 1291. Close to the church are several stones with a Christian text and cross inscribed. The oldest parts of the present red-brick church are from the 1300s. In the late 1400s the church was enlarged to the appearance it has today. The church has been modified both internally and externally several times, among other things after the fires in 1699 and 1889. There are lot of well-preserved mural paintings in the walls.