The oldest and most robust Gothic castle in the area below the Krušné Mountains, called in the period fashion Riesenburg, the Giant's Castle. The construction of the castle was initiated by Bohuslav I and in 1241 - 1250 the construction was completed by his son Boreš II. The Rýzmburks were one of the oldest nobility families in Bohemia, and the son, just like his father, held the position of the highest groom of the chamber of King Wenceslas I. The Rýmzberks were also known under the name of Hrabišici, because of their family coat-of-arms which depicts a rake (hrábí); the name of Hrabišici became popular in later years.