The castle was built in 1191 by the brothers Hermann and Bernhard Berkule near the village of Holthusen, first mentioned in 1170, to control the associated farms and the road from Warburg to Kassel. In 1224, the Prince Bishop of Mainz, Siegfried II von Eppstein, laid claim to the castle, which the Lords of Berkule had given in fief to the Prince Bishop of Cologne, Philipp von Heinsberg.
However, the growing oppression of the associated farmers by the castle construction meant that some farmers tried to flee to the newly created and expanded town of Warburg. Around 1240, the old town of Warburg therefore had to undertake to only accept peasants from the knight Hermann Berkule with his consent. But this peace didn't last long, because in 1245 the Holthusener fired arrows at the old town again. The Berkule Knights were able to expand their power even further by building the Calenberg Castle
Finally, on November 6, 1294, the sovereign, Bishop Otto von Rietberg of Paderborn, concluded an alliance with various towns to ensure peace in the country. The bishop pledged to do everything in his power to protect those involved in the destruction of the castle, who had imprisoned or executed men from the castle garrison from vengeful raids, damage, arson or other harassment. Sanctions were threatened for those who would fire arrows at the cities. Then the castle was stormed and destroyed by soldiers from Warburg, Marsberg, Höxter, Fritzlar, Hofgeismar, Wolfhagen and Naumburg. Some of the captured knights were executed. Johann Berkule submitted to the bishop, who made him one of his castle men in Warburg. Around 1300, Calenberg Castle also fell to Paderborn Bishop Otto, who occupied it with his followers.
After its destruction, the Holsterburg was covered with a mound of earth, probably also for symbolic reasons, to erase the Berkule family and their ancestral seat from the memory of posterity. Under the hill, the complex has been preserved as it was in 1294.
The overgrown hill of the former Holsterburg in the Diemeltal had previously been classified by experts as a so-called moth. A survey in 2010 revealed a corner block at the edge of the hill. In the summer of 2010, an excavation team from the Department of Medieval and Modern Archeology of the Regional Association of Westphalia-Lippe, headed by Andrea Bulla, began excavating the castle complex. Since then, excavation campaigns have been carried out annually. From 2015, archaeologist Kim Wegener led the excavations at Holsterburg. With the conclusion of the excavation campaign in 2017, the archaeological excavation work on the Holsterburg was officially declared over.
During the work, the archaeologists found an octagonal structure from the Staufer period with a 1.70 meter wide double-shell limestone wall, along which plastered blocks up to 1.38 meters long had been processed.
Until the excavations, it was assumed that it was a moated castle. New archaeological investigations by LWL Archeology for Westphalia have meanwhile disproved this.
During the excavation campaign in 2017, a one-piece ivory double comb with intricately carved motifs was found. It is dated to the third quarter of the 12th century and is considered a liturgical crest.
The Holsterburg is a lowland castle built as an octagon, a very rare design for castles. It is the only one of its kind in Westphalia and one of only three octagonal castles in Germany. Comparable but somewhat later octagonal ring structures were the Kilchberg Castle in Tübingen and the Egisheim, Guebwiller and Wangen Castles in Alsace; only a few decades later the famous Castel del Monte was built.
The octagonal ring wall has a length of about 87 meters. The outer shell is made entirely of carefully worked, regularly arranged smooth ashlars, the corner joints of almost seamlessly set, finely smoothed corner ashlars. The wall segments show variations of herringbone patterns and joint nets with fine joint strokes on many of the stones on the visible side. The two shells of the wall are connected by press mortar made of sand and rubble. Overall, the wall encloses an area of ??428 square meters with a diameter of 26 meters.
The discovery of a limestone canal, which runs flush with the inner lining of the ring wall, attracted a great deal of attention. It was probably part of a heating system.
Inside the castle there were three buildings: one in the north-west, one in the east and the adjoining peripheral development in the south-west and south of the castle. In the middle of the northern inner courtyard was the keep, the location of which can still be seen today in the form of a he excavation pit shows. The pit was filled with stone material from the demolition.
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