Question: Where was the builder of Walferdange Castle a Prince of?
Related documents: [0]  [DOC] William I (Willem Frederik, Prince of Orange-Nassau; 24 August 1772 – 12 December 1843) was a Prince of Orange and the first King of the Netherlands and Grand Duke of Luxembourg. [END] 
[1]  [DOC] 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. It is now part of the University of Luxembourg. [END] 
Answer: 
Orange
Orange