Question: Where was the builder of Walferdange Castle a Prince of?
Sentence (from "Walferdange Castle"): Walferdange Castle (French: "Château de Walferdange" ), located in the small town of Walferdange in central Luxembourg, dates from 1824 when William I of the Netherlands who was also Grand Duke of Luxembourg built it as a stud farm.
Relevant evidence: Yes