Horneburg Castle

The first mention of Horneburg dates back to 1220 in a document confirming its affiliation with the Richrode manor. Until 1418, it was the ancestral seat of the Lords of Oer. In 1389, Heydenrich von Oer acquired the Oer imperial estate, including Horneburg, from the Cologne Cathedral Chapter and expanded and fortified the castle. His son, Heinrich von Oer, attempted to assert sovereign rights in the surrounding area but was defeated in 1418 and forced to leave the castle. After 1420, the electoral Cologne treasury, an important administrative office for estate management, was moved from Recklinghausen to Horneburg, as the castle offered better spatial conditions. In 1431, the Archbishop of Cologne fully took possession of Horneburg.