Burgruine Rosenau

Burgruine Rosenau stands in Königswinter, Germany; the identity of its builders is unknown, although the site probably belonged to the Archbishopric of Cologne and fit within that territory’s system of castles.

The place appears in writing on 27 February 1222, when it was called Rosenau and its owner was Dietrich von Dorndorf. After that entry he took the name Dietrich von Rosenau. In November 1243 Dietrich’s widow, Agnes, sold the property to the monastery of Heisterbach, and the sale contract granted the buyer the explicit right to destroy the castle, a provision noted in the record as highly unusual. A later agreement was drawn up in 1249 after a daughter‑in‑law raised an objection to the 1243 transfer.

Around 1250 the monastery carried out the destruction of the fortress, and the stones from the demolished walls were probably reused in building work at the monastery. For centuries the ruined site remained part of the landscape without the medieval structure standing intact.

By 1885 a small settlement called Rosenau lay close to the ruin, with twenty residents in three buildings. Between 1896 and 1898 the landowner Anselm Bachem erected a hotel on the site. Materials for that project were delivered by a temporary rail siding from the Heisterbacher valley railway laid in May 1896, the shell of the hotel was finished by late November 1896, and the hotel finally opened on 4 May 1898 after a collapse of the west façade delayed the inauguration. Work to improve access followed: an old cart track was upgraded and opened as a road on 1 April 1899, and in 1933 a motor road from Heisterbacherrott to Rosenau was constructed as a public employment measure.

In 1902 excavation during path improvement and the building of a pavilion revealed sections of ancient walls described at the time as forming an elongated rectangle roughly 18 by 30 metres. The hotel suffered heavy damage from explosive bombs on 4 February 1944, and the structure was taken down in 1953 by its then owner, IG Bergbau und Energie. The surviving medieval masonry on the hill was stabilised in 1990 and 1991 with support from IG Bergbau und Energie, the state of North Rhine‑Westphalia, and the city of Königswinter.