Château de Freundstein is a ruined castle in the commune of Goldbach-Altenbach. The castle was recorded in 1297. It ownership was shared between the abbey at Murbach and the bishops of Strasbourg. It waas given as a fiefdom to the Waldner family who still own it. In 1441, it was attacked by the Mulhouse and in 1525 by rebellious peasants. It was restored in the 16th century, but abandoned shortly afterwards. The ruins were used as a military observatory during the First World War. The ruins consist of sections of wall from the high castle, with loopholes and more recent openings.
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.