Wildenburg, Medieval castle ruin in Wildhaus-Alt St. Johann, Switzerland

Wildenburg is a castle ruin perched on elevated terrain in the Alpine valley of Wildhaus-Alt St. Johann. The remaining stone walls show construction methods from the medieval period with characteristic features typical of fortified dwellings of that era.

The Wildenburg was built around 1200 by the Barons of Sax. In 1313 it was sold to Count Friedrich IV of Toggenburg, passed by inheritance to the Lords of Raron in 1439, and was sold to the Abbey of St. Gall in 1468. Shortly after 1660 a lightning strike set it on fire and it burned out.

The ruins serve as a visual anchor in the valley landscape and visitors often use the site as a waypoint during their mountain walks. The remnants reflect how fortified structures once shaped settlement patterns in this Alpine region.

The ruins are accessible via marked hiking trails that lead through the mountainous terrain from various starting points in the valley. Visitors should bring sturdy footwear and weather-appropriate clothing, as the paths are exposed and subject to changing mountain conditions.

Beneath the ruins lies the roughly 100-metre-long machine-gun cavern "Wildenburg" A 6005, built during the Second World War. The castle is also the setting of several legends. Visitors often overlook both the wartime structure and the stories tied to the site.