Radyně Castle, like the similarly conceived Kasperk, represents the height of the 14th-century trend towards the merging of castle buildings.
When the castle of Starý Plzenec fell into disrepair in the first half of the 13th century, it was necessary to build a new centre of royal power for the administration of the region of Plzeň. Construction apparently began in 1353, during the rule of Charles IV, and was completed in 1361. The original name of Karlskrone (Charles' Crown) did not become commonly used in the district, and the castle gradually took the name of the hill on which it was built - Radyně.
The burgraves who governed the region were based in Radyně, and by the end of the 15th century it had been acquired by the Šternberks (1496–1561), who settled at the more comfortable castle at Bechyně. Its counterpart at Radyně, which was accessible only with difficulty, started to fall into disrepair, and its fate was sealed in the first quarter of the 16th century when it was burned down. As early as 1558, record indicated that it was abandoned, and not even the affluent Černín of the Crudenice family, owners of the castle as well as the surrounding district in the 18th century, invested in repair work. The mysterious abandoned ruin had to wait until the coming of the Romantic movement in the 19th century for more interest to be shown in it. Minor repairs and alterations were however destroyed by fire in 1886.
In recent years, the castle has been progressively renovated, and a permanent exhibition devoted to its history can now be seen. The tower is open to visitors of the castle, and its observation point affords wonderful views.
References:Celje Castle was once the largest fortification on Slovenian territory. The first fortified building on the site (a Romanesque palace) was built in the first half of the 13th century by the Counts of Heunburg from Carinthia on the stony outcrop on the western side of the ridge where the castle stands. It had five sides, or four plus the southern side, which was a natural defence. The first written records of the castle date back to between 1125 and 1137; it was probably built by Count Gunter. In the western section of the castle, there was a building with several floors. Remains of the walls of this palatium have survived. In the eastern section, there was an enclosed courtyard with large water reservoirs. The eastern wall, which protects the castle from its most exposed side, was around three metres thicker than the rest of the curtain wall. The wall was topped with a parapet and protected walkway.