Diamond Jubilee celebrations finally began on Saturday. (If you're thinking, "wait... hasn't the Jubilee been happening for months now?", it's just because Britain has been having the longest pre-party ever.)

Queen Elizabeth II, who celebrates 60 years of reign this weekend, officially kicked off the four-day Jubilee on Saturday at the annual Epsom Derby races. The King's Troop fired a 41-gun salute in London to mark the official start to the festivities in central London. At the races, the crowd numbered 130,000 strong, many of them decked out in endless variations of the Union Jack, to watch a horse named Camelot take the grand prize.

Clad in royal blue (get it?), Her Majesty feted the day at the race with a host of family members, including her husband Prince Phillip; Prince Andrew and Prince Edward; and Andrew's daughters Princess Beatrice and Princess Eugenie. Both ladies donned fascinators, Eugenie in a white-striped bonnet and Beatrice in a spaghetti-free pillbox hat.

Our pick for Guest We Didn't Expect To See: Mischa Barton, who showed up in a sparkly black top hat. (No pandas seemed to be present.)

Across the country, Britons celebrated with street parties and days off work. On Sunday, Her Majesty will attend a luncheon and travel down the Thames river on a barge.

See some pics of the day below!

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  • Princess Beatrice & Princess Eugenie

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  • Princess Eugenie

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  • Mischa Barton

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