Listed as a cultural heritage, it is located in Altenberg, now part of Odenthal in the Rheinisch-Bergischer Kreis, North Rhine-Westphalia, Germany.

The Castles name transferred to the county and the counts, today the Area is called Bergisches Land.

[1] The archbishop of Cologne, Konrad von Hochstaden, laid in 1259 the foundation of a larger church "St. Mariä Himmelfahrt" (Assumption of Mary).

Count Fürstenberg von Stammheim bought the ruins in 1833 and turned them over to the Prussian king, Friedrich Wilhelm IV, who was fond of medieval history.

He suggested already in the 1830s that the Altenberger Dom should be used by both Catholics and Protestants as a simultaneum, and finalized the idea in a royal decree of 1856.