Schloßberg was a castle and Benedictine monastery hill built by the Emperor Lothar III around 1136 near Chemnitz. The monastery existed almost 400 years and was rebuilt many times. The last Gothic appearance was built between 1488 and 1522. Around the 1540 Benedictines left the site which fell to the Saxon Electors. The building was used as an administration and hunting lodge.In 1931 the new city museum was opened.
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.