The remains of the Castle can be visited
Landskron Castle

Near Bad Neuenahr-Ahrweiler in Rhineland-Palatinate, the imperial castle remains of Landskron, a high medieval hilltop castle, stand on a basalt cone. As the ancestral seat of the Burgraves of Are, it played a role in the conflicts between the Staufer and Welfen dynasties.
History+
Construction of Landskron Castle began in 1206 by order of King Philip of Swabia to secure the Frankfurt-Aachen coronation road and fortify the imperial territory around Sinzig, Remagen, and Heimersheim. Gerhard von Sinzig was appointed the first castle administrator. After Philip's assassination, Otto IV continued construction, and after Otto's death, Frederick II retained Gerhard in his office. The Burgraves of Landskron, particularly the Gerhard line, were involved in German imperial politics for centuries.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Axel Hindemith / CC BY-SA 3.0 via Wikimedia Commons
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: 50.5514, 7.1723