From high up on the rock of Susa, this castle has witnessed millennia of history. In 1046, Countess Adelaïde received here her husband Otto, Count of Savoy, bringing him the dowry of the marquisate of Susa and the county of Torino.
The Castle was presumed to be built in the Middle Ages, this also explains the presence of mullioned windows on the walls, a typical element of that era. Over the years he underwent several restorations, especially in the 18th century, which gave him the present appearance. Today, it houses in its interior the Historical Archives, the Civic Museum and the Library.
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.