Burg Altraderach

Altraderach Castle, also called the Old Castle or Little Heathen Palace (Heidenschlösschen), is a levelled castle in the area between Unterraderach and Raderach. The still easily visible burgstall lies in the parish of Kluftern in the borough of Friedrichshafen in the county of Bodenseekreis in the German state of Baden-Württemberg.

Source: Wikipedia (CC BY-SA 4.0) — https://en.wikipedia.org/wiki/Altraderach_Castle