The remains of the Castle can be visited
Homburg Castle

The Homburg castle ruin, a hilltop castle, is located above Stadtoldendorf in the Holzminden district, Lower Saxony. This complex was characterized by a bailey and a small main castle, each with its own keep.
History+
The origins of the Homburg may date back to an earlier castellum called Wikanafeldisten, mentioned at the end of the 10th century. In the 12th century, Siegfried IV. of Boyneburg had the castle built to protect Amelungsborn Monastery, which stood in direct competition with the castle of the Counts of Everstein. After Siegfried's childless death in 1145, the castle changed hands several times, including Count Hermann II. of Winzenburg and later the Diocese of Hildesheim. Duke Henry the Lion claimed the Homburg in 1152, but after his outlawry in 1180, it fell back to the Prince-Bishopric of Hildesheim. A structural division of the castle manifested when, in 1183, Bodo of Homburg and the Counts of Dassel each received one half as a fief. From about 1247, the castle was undivided in the possession of the Lords of Homburg, who granted Stadtoldendorf town rights in 1255.
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This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 51.9016, 9.6426