His Royal Highness Prince Constantijn of the Netherlands Attends the Opening of the European Youth Parliament. Alexandra 10 years ago Advertisements On November 11, 2012, His Royal Highness Prince Constantijn of the Netherlands attended the opening of the European Youth Parliament held inside the Hall of Knights in Den Haag. RelatedHis Royal Highness Prince Constantijn of the Netherlands Opens an Exhibition in Brussels. (VIDEOS)April 23, 2013In "Dutch Royal Family"Their Royal Highnesses Prince Constantijn and Princess Laurentien of the Netherlands Attend a Concert at the Ridderzaal.November 10, 2013In "Dutch Royal Family"His Royal Highness Prince Constantijn of the Netherlands Attends the Oskar Back Vioolconcours Finals in Amsterdam.April 28, 2013In "Dutch Royal Family"