The remains of the castle can be visited
Stiefler Castle

Near St. Ingbert in Saarland is Stiefler Castle, a small castle ruin. It is one of Germany's oldest castle ruins, and its original function is unclear.
History+
Stiefler Castle was built in the early Middle Ages. Archaeological findings suggest that an outwork already existed around 450 AD. It is presumed that the complex served border security from the 10th century onwards. In the late Middle Ages, the castle fell into disrepair. In 1875, the site was attributed by the Historical Association of the Palatinate to Weinantstein Castle, which was granted to Count Palatine Ruprecht III in 1398 and subsequently disappeared from records. The original motte-and-bailey castle consisted of a rectangular stone structure measuring 8.4 by 11.4 meters.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: https://commons.wikimedia.org/wiki/File:Stiefeler_Schloss_St._Ingbert.jpg
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: 49.2579, 7.0929