Altena Castle was erected by the brothers Adolf and Everhard von Berg around the year 1108 after Henry V granted them land in Sauerland. On Wulfseck Mountain they built their castle, which they named Wulfeshagen, later Altena. This is one of the three legends of the establishment of the county of Altena and the building of the castle.
After the acquisition of Mark near the city of Hamm in 1198, the counts of Altena took Mark Castle as their primary residence and called themselves the Counts of the Mark. They occasionally inhabited Altena Castle and from 1392 onward it was used as a residence for the county bailiff (Amtmann).
In 1912, Richard Schirrmann established the world's first youth hostel within the castle, which is still in use today (Jugendherberge Burg Altena).
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.