Ehrenfels Castle was (re-)built about 1212 at the behest of the Archbishop of Mainz as a defensive work against the constant attacks by Elector Palatine Henry V, who, as Imperial vicar of Franconia, strived to cut down the archbishop's reach. Mainz staffed the castle with Burgmannen and erected a customs post controlling the shipping on the Rhine, supplemented by the Mouse Tower below at the river. Heavily damaged in the course of the Thirty Years' War, the castle was finally devastated by French troops under the command of Lieutenant General Nicolas Chalon du Bléduring the 1689 Siege of Mainz.
The ruin can be reached from Rüdesheim via a hiking trail through the vineyards. The interior however can only be visited in guided tours by prior appointment.
References:The Château du Lude is one of the many great châteaux of the Loire Valley in France. Le Lude is the most northerly château of the Loire Valley and one of the last important historic castles in France, still inhabited by the same family for the last 260 years. The château is testimony to four centuries of French architecture, as a stronghold transformed into an elegant house during the Renaissance and the 18th century. The monument is located in the valley of Le Loir. Its gardens have evolved throughout the centuries.