King’s Day is one of the biggest nationwide festivals in the Netherlands. Formerly known as Queen’s Day and celebrated on April 30, King’s Day is now celebrated on April 27 (26th this year!), the birthday of Willem-Alexander, who ascended the throne in 2013. Queens/Kings’s day has been celebrated since 1885, and is a day when everyone in the Netherlands wears orange, in honour of the Dutch royal family of Orange-Nassau. Residents often take to the streets for a large, nationwide street-sale, and then head out for a day of partying in cities around the country. https://www.holland.com/global/tourism/getting-around/information/the-royal-family/kings-day-in-holland