Princess Charlotte and Prince George Are as Cute as Ever in New Royal Family Photo

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Happy Birthday, Queen Elizabeth II!

The royal turns 90 on Thursday and in celebration of her milestone birthday, the British Monarchy released a series of official family photos of the royal family over social media, shot inside Windsor Castle by famed photographer Annie Leibovitz.

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In the first pic from the collection, which was posted on Wednesday, it's hard not to notice the Duke and Duchess of Cambridge's 11-month-old daughter, Princess Charlotte, who was all smiles while sitting on her great-grandmother's lap. Standing right next to her, clad in a navy blue cardigan and burgundy trousers, is her big brother, 2-year-old Prince George.

"The Queen surrounded by her two youngest grandchildren and her five great-grandchildren," the caption reads. Also pictured -- from left to right -- are James, Viscount Severn; Lady Louise; Mia Tindall; Savannah Phillips; and Isla Phillips.

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The British Monarchy also released a solo shot of the Queen on Facebook, wearing an all-blue ensemble and gracefully posing next to her four adorable dogs -- corgis Willow and Holly, and dorgies Vulcan and Candy.

The third image features the queen sitting next to her daughter, Anne, The Princess Royal, in the castle's White Drawing Room.

It doesn't get much more regal than that!

WATCH: Prince George Poses for the Most Adorable Royal Family Portrait

On Tuesday, Prince George looked equally as cute in a pic of himself posing with the queen, dad Prince William and grandfather Prince Charles. As ET previously reported, the photos were released by the Royal Mail as a set of four, first-class stamps commemorating the queen's birthday.

Hear more on that photo shoot in the video below.