The King's birthday
Please, foreign visitors, don't mix up the dates! When Queen Beatrix was still the monarch of the country, the Dutch would celebrate her birthday on April 30. However, when her son mounted the throne in 2013, Queen's Day became King's Day, and his birthday is on April 27. So don't get fooled by old travel guides! There's always a few tourists showing up in Amsterdam on April 30, completely dressed in orange, and it's hilarious for the locals - but not so much for the tourists.