Prince George celebrates his 5th birthday: Look back at his most adorable moments

Prince George, the heir to the British throne and the oldest child of Prince William and Princess Kate, is celebrating his fifth birthday Sunday.

George is spending his birthday week in Mustique on a family vacation that includes not only his parents and siblings, Princess Charlotte and Prince Louis, but also his aunt and uncle, James and Pippa Matthews, and his maternal grandparents, Michael and Carole Middleton.

On Saturday, Kensington Palace shared a picture on Twitter of a beaming Prince George to mark his birthday and thanked "everyone for your lovely messages."

The photograph was taken in the garden at Clarence House by Matt Porteous, following the christening of Prince Louis on July 9.

“The Duke and Duchess of Cambridge are very pleased to share a new photograph of Prince George to mark His Royal Highness's fifth birthday tomorrow.” Kensington Palace said in a statement

When George was born at St. Mary's Hospital in 2013, his birth caused a media frenzy around the world and in the U.K., where Brits celebrated the birth of their new heir.

To mark George's birthday, the Royal Mint has issued a £5 (around $6.50) commemorative coin, which is available to the public for purchase, features an image of St. George, the patron saint of England, and a dragon.

Now a student at St. Thomas's Battersea School in London, George has had a busy few months with the royal family.

He was a page boy at the May 19 wedding of his uncle, Prince Harry, to Meghan Markle, attended Louis' christening, and made an appearance with the royal family at Trooping the Colour.

Take a look back at some of George’s most adorable moments through the years.