Freudenstein castle is situated outside the boundaries of the Jáchymov on a hill above the northwest edge of the town. Built by Stephan Schlick between 1516-1517 it was used for protection. Reportedly, illegal minting of the first Jáchymov thalers started in its cellars in 1519. In 1547, the castle became royal property and was used as the seat of the Royal Inspectors of the Mines. During siege by the Swedish army In 1634, the castle was considerably damaged by artillery and burnt down. Afterwards it wasn't cared for and it withered away. The masonry of the defensive walls has been worn down and used as building material.Only two towers were upstanding. A larger tower in the northwest corner, called Šlik (Schlick) tower, still exists in its full height of 19 m. In the southwest corner, there is a lower cylindrical tower called the Prachárna (powder store), 12 meters high. In the 18th and 19th centuries, the tower was used to store gunpowder for mining purposes.
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.