In Amsterdam there’s an outdoor concert for nearly 1 million people as the main focus of the celebrations but it generally involves wandering the streets dressed in orange, with orange dyed hair in what has been termed ‘orange madness’, drinking as much as you possibly can.
If you’re planning on visiting, and it comes highly recommended, then make sure you’re not travelling to or from the Capital on the day, as transport is severely disrupted to cope with the millions of people on the streets. Instead get there the night before on what is known as Queen’s night and start the party early. On the evening before people hit their local squares, town centres and streets and party through the night all the way into Queens Day proper.