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 Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.