The ruins of Radyně Castle, 567 m above sea level, dominate the surroundings. In order to enjoy the view of the castle even at night, the castle has been illuminated since 2006. The castle tower is 22 metres high and 114 steps lead to its top platform.
The original name Karlskrone did not fell on a fertile soil in the Czech environment; after the death of Charles IV, the castle became to be called Radyně, which was the name of the hill and the lydite rock on which it was built. The builder of the castle was most probably Michael Parler from the family of the Prague court master builder Peter Parler. The construction was supervised by Vít Hedvábný.
Most of the castle administrators –burgraves – were members of the gentry from the Pilsen region. Their duty was to monitor and ensure the safety of the trade route from Nuremberg via Regensburg to Prague, to exercise judicial authority over direct subjects of the monarch, and they probably also had the power to try and execute criminals. The official function of the first royal burgrave at the castle was probably entrusted to Zdislav Chlup, who successfully led the construction of the castle; the last was most likely Racek (Raczko), during whose reign, around 1550s, the castle burnt down. In the following years, the castle was successively owned by the following noble families: the Lords of Šternberk(1496–1561), the Kokořovec family of Kokořov (1561–1710), the Czernins of Chudenice (1710–1816) and the Wallensteins (1816–1920). In 1920, the village of Plzenec bought the castle and the forests from the last owner. The castle was taken over by the newly founded Society for the Rescue of Radyně and Hůrka.
In the castle tower there is a permanent audiovisual fairy-tale exhibition featuring mysterious creatures from the stories about Radyně Castle and a historical exhibition with a model of Radyně Castle; an observation telescope is available on the tower lookout platform along with horizon maps. At present, the castle is in the care of the town of Starý Plzenec and over several years it has undergone gradual reconstruction to the final form that we can admire today.