Rötteln Castle (German: Burg Rötteln), located above the Lörrach suburb of Haagen, lies in the extreme southwest corner of the German state of Baden-Württemberg just 10 kilometres (6 miles) North-East of the Swiss City of Basel. The fortification was one of the most powerful in the southwest, and today is the third largest castle ruin in Baden.
The ruins of the castle are situated on a widely visible forested hill 422 metres (1,385 ft) above sea level. The keep lies on a spur projecting from the steep sided east side of the lower Wiese valley.
read more at https://en.wikipedia.org/wiki/R%C3%B6tteln_Castle or http://www.burgruine-roetteln.de/