Wartenstein castle was built around 1206 by Konrad von Zwiefalten. The castle is mentioned for the first time in 1208 and later owned for several families. In 1341 it was rebuilt and repaired by abbot Hermann II of Arbon. After the middle of the 16th century sources describe the castle dilapidated. The Abbey Pfäfers gave in 1586 the worthless site to the local residents as a quarry.
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.