Dutch King Willem-Alexander, Queen Maxima, Princess Laurentien and Prince Constantijn (R to L) wave to people on the balcony of Noordeinde Palace on the Prince's Day in The Hague, the Netherlands, Sept. 18, 2018. "Prinsjesdag", the Prince's Day, is held every year in The Hague on the third Tuesday of September, which marks the opening of the parliamentary year. (Xinhua/Rick Nederstigt)