Freudenstein castle is situated on a hill above the northwest edge of the town, for the protection of which it was built in 1516–1517 by Stephan Schlick. Reportedly, illegal minting of the first Jáchymov thalers started in its cellars in 1519. In 1548, the castle became royal property and began serving as the seat of the Royal Inspectors of Mines. In 1634, during the siege by the Swedish army, the castle was considerably damaged by artillery and it was burnt down. 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.