(CNN) -- While much of the world's attention will be fixed on a certain royal wedding in London, Prince William's nuptials are not the only royal affair happening this weekend.
The orange craze, or "oranjegekte" in Dutch, returns to Netherlands on Saturday, when millions of revelers wearing head-to-toe orange will hit the streets across the nation to celebrate Queen's Day.
The Dutch royal occasion has been celebrated for over 100 years and is the annual official celebration of the Queen's birthday.
The national holiday is a chance for revelers to take part in "vrijmarkts", or free markets, play traditional Dutch games with their families, listen to music and get decked out in their best Saturday orange.
The tradition goes back to 1891, when the holiday was created to celebrate the August birthday of Queen Wilhelmina. Queen's Day was moved to April 30 with the coronation of Queen Juliana in 1948, and has remained on that day during the current reign of Queen Beatrix.
Orange is the official color of the Queen and the royal family, descendants from the House of Orange-Nassau that has played a political role in the Netherlands for roughly half a millennium.
"Around the world, people know Holland for the orange clothes, and Queen's Day is the biggest orange party in the country," says Janneke Hendrikx, a public relations officer for the Netherlands Tourism Board.
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The night before the holiday, "Koninginnenacht" or Queen's Night, has become an even bigger event for young adults across the country in recent years, and many revelers take to the bars and streets of Holland for an all-night party that lasts until the Queen's Day free markets open at sunrise.
"I am definitely one of those people," laughs Joanne Zonderland, a 28-year-old designer living in Amsterdam. "I usually go out (to the bars) until around 4 a.m., then I go home and sleep until 5:30 a.m. Then I take the tram to the free market."
The Queen's Day free markets are giant, often city-wide street markets where young children can sell toys they no longer want, and adults sell used clothing, records, books and antiques.
Marieke Breijer, a 25-year-old journalist who grew up in the Dutch town of Nieuwerkerk aan den IJssel, says that while the free markets in smaller locales have a more casual feel to them, the free markets in bigger cities are serious business.
"In Amsterdam, for instance, people are really serious about the free market," she says. "The hardcore people sleep on the streets (the night before) just to keep their places to sell stuff in the morning."
For many free market veterans across the country, the Queen's Day clothing sales at the market are the year's best opportunity to snatch up fashion steals at discount prices.
"Everything is incredibly cheap," says Zonderland, who has participated in the Amsterdam market for the past seven years. "The best clothes in my wardrobe consist of things that I've got from the free markets."
In addition to the free markets, residents of big cities like Amsterdam, Rotterdam and The Hague gather in the city squares to drink and listen to music.
Many of the expected million people visiting Amsterdam on Queen's Day will spend their day drinking beer and riding boats along the city's famous canals.
"Everybody drinks beer," says Zonderland of the drink of choice at Queen's Day. "It's the cheapest, it's the handiest, and everybody has it."
Thousands of visitors to the city will eventually end up in Museum Square, says Breijer, where stages are erected to showcase some of Holland's biggest musical acts at the yearly celebration.
Children celebrate Queen's Day with Dutch games like "koekhappen," a game where children jump to eat traditional-style cakes dangling from a string without using their hands.
"It's like bobbing for apples, except you're jumping for cake," says Zonderland.
Another game played on Queen's Day is "spijker poepen," a game where children tie a nail around their waist with a string and attempt to lower the dangling nail into a glass bottle.
Each year, Queen Beatrix and her family join in the family fun and festivities in two Dutch towns. This year, residents of Weert and Thorn will flood the streets in the hopes of shaking hands and taking part in games with royalty.
While once a quite open affair, Janneke Hendrikx says security surrounding the Queen's yearly visits has been ratcheted up since the 2009 Queen's Day tragedy in Apeldoorn.
That year's festivities were marred when a man drove his car into the Queen's Day parade, narrowly missing the Queen's open double decker bus and killing seven bystanders.
The tragedy sparked a national debate about whether the royal family should continue to play such a public role in Queen's Day celebrations.
But following the Queen's insistence that she would continue to participate in the parades and walk with citizens in the street, the holiday "is still the open and friendly celebration that it used to be," says Hendrikx.
Queen's Day is also observed in Aruba, Curacao and Sint Maarten -- constituent countries of the Kingdom of the Netherlands -- and in recent years, the holiday has been celebrated in London and Madrid.
Breijer, who celebrated Queen's Day last year in Utrecht, a city in central Holland, says the holiday is a rare chance for national unity.
"The best part of Queen's Day is spending time with friends and everyone coming together to have some innocent fun," she says, "just like we celebrated during the World Cup last year."
