The remains of the Castle can be visited
Reitersdorf Castle (Ruin) (Bad Honnef)

The Reitersdorf ruin in Bad Honnef is one of the oldest visible traces of the city, which was first documented in the 9th century.
History+
The locality of Reitersdorf was first mentioned in a document in 866 as "villa rateresthorp" and in 893 as "Retersdorpht". In 1222, Reitersdorf served as a messenger station for Prüm Abbey. From 1270, Johann von Heinsberg began constructing the castle, possibly as a replacement for Löwenburg Castle, from which he had been expelled. The settlement of Reitersdorf developed west of the castle near the Rhine and also included the church "St. Göddert". In 1288, the castle, referred to as "Castrum Reyterstorp", became a fief of the Count of Jülich, who had it expanded. By 1317, the complex was largely destroyed in military conflicts with the Archbishop of Cologne.
Source: Wikipedia · Licence: CC BY-SA 4.0
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: 50.6510, 7.2178