The remains of the Castle can be visited
Willenburg Castle (Ruin)

The Willenburg ruin, also known as “Schlössle,” is a High Medieval architectural site in the Black Forest. It is located above Schiltach in the district of Rottweil and once served to control an important trade route. Its rediscovery in the 20th century makes it an attraction for history enthusiasts.
History+
The origins of Willenburg date back to around 1100. It was likely built by the Dukes of Teck, a collateral line of the Zähringer, or even by the Zähringer themselves. Its primary purpose was to supply travelers on the old pass road to Rottweil and to collect tolls. From about 1250 onwards, Willenburg lost its significance as the newly established town and castle complex of Schiltach took over its functions.
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: 48.2856, 8.3721