The earth and timber stronghold Gerdauen was constructed by the Teutonic Knights in 1270. After a subsequent Prussian uprising, the Knights were too weak to keep hold of all their fortresses. Gerdauen was burnt down, but once the Prussian uprising was put down, the Teutonic Knights returned here and began to raise new fortifications. By 1310, a new stronghold had been completed. At that time it was guarded by embankments, moats and shelters. Inside the ring of fortifications, stone and brick buildings for a convent of Teutonic brothers were constructed.
Initially the Knights planned that Gerdauen would become a seat of a commander, known as komtur. But this idea was soon relinquished because of the proximity to the Lithuanian lands and frequent attacks staged by Lithuanian troops. Gerdauen for example was attacked in 1336, 1337 and in 1366.
Although in 1406 Gerdauen Castle was surrounded by a ring of fortified walls less than half a century later, in 1455, which was during the Thirteen Years' War, the fortress was severely damaged. In 1670 it stood empty. Soon afterwards it was sold to a private owner. All that had remained of the original buildings were the cellars.
In 1872 a new beautiful palace was raised on this location. Gerdauen flourished until 1814, that is until the outbreak of World War One. In that year, the town was a witness and a victim of a bloody fight with the Russian army. Gerdauen was not rebuilt until 1921.
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.