The Duke and Duchess of Cambridge are celebrating their 10th wedding anniversary on April 29 - so we can't help but get a little nostalgic as we remember their royal nuptials back in 2011.
And while Kate's Alexander McQueen bridal gown was the ultimate show-stopper, there were plenty of famous wedding guests that also made headlines with their fashion choices.
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Westminster Abbey was filled with a sea of statement hats for the services, which saw royals from around the world and A-list stars attend. Whether it's a bandeau, a fascinator or a wide-brimmed number - headwear is essential uniform at a royal wedding. So let's look back at some of the most memorable pieces...
Who could forget Princess Beatrice's incredible Philip Treacy creation? We think the royal was ahead of her time with her whimsical, statement choice - which matched perfectly with her chic Valentino outfit.
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Princess Eugenie's headwear was also designed by milliner Philip Treacy, who created many of the hats that adorned the guests on William and Kate's big day.
The royal revealed that the sisters had been hurt by the backlash towards their fashion choices in an interview with British Vogue.
"There was a horrible article that had been written about Beatrice and she got really upset. We were just about to step out and she had a bit of a wobble and cried. I was looking after her," she explained. "And then about an hour later, I had a wobble and started crying and Bea was there for me."
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Victoria Beckham - who was pregnant with daughter Harper at the time - also memorably wore a hat made by Philip Treacy.
A lovely moment between the Queen, the Duchess of Cornwall and Carole Middleton at the royal nuptials. Her Majesty opted for a bold yellow hat, while Camilla wore a neutral design.
Mother of the bride Carole perfectly matched her hat to her Catherine Walker outfit.
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The late Tara Palmer-Tomkinson wore a bold blue dress, gloves and clutch bag, which she teamed with a matching Philip Treacy creation.
Lady Frederick Windsor, also known as Sophie Winkleman, looked beautiful in her statement headpiece and pearl accessories.
Both the Countess of Wessex and Princess Anne opted for pretty floral numbers.
Joss Stone memorably opted for a wide-brimmed hat with floral embellishments for the Duke and Duchess' royal wedding day.
Crown Princess Victoria of Sweden teamed her tangerine midi dress with a matching hat.
Zara Tindall - then Zara Phillips - also wore a Philip Treacy number, and what a showstopper it was!
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Earl Spencer's daughters Lady Amelia, Lady Eliza and Lady Kitty all opted for architectural headpieces, too.
Prince Harry's date for the royal wedding was then-girlfriend Chelsy Davy, who wore a subtle fascinator with net detailing.