Dutch Princess Alexia, Princess Amalia, King Willem-Alexander, Queen Maxima, Princess Laurentien and Prince Constantijn (from L to R) wave to people on the balcony of Noordeinde Palace on Prinsjesdag, Prince’s Day, in The Hague, the Netherlands, on Sept. 17, 2024. The third Tuesday in September is Prince’s Day in the Netherlands. It marks the opening of the Dutch parliamentary season, and on this day the reigning monarch outlines the government’s plans for the year ahead.