Stolzenfels Castle (German: Schloss Stolzenfels) is a castle or palace near Koblenz on the left bank of the Rhine, in the state of Rhineland-Palatinate, Germany. Stolzenfels was a ruined 13th-century castle, gifted to the Prussian Crownprince, Frederick William in 1823. He had it rebuilt as a 19th-century palace in Gothic Revival style. Today, it is part of theUNESCO World Heritage Site Upper Middle Rhine Valley.