Prince William's Romantic Anniversary Gift to Kate Middleton Once Belonged to Princess Diana

We're wishing a very happy anniversary to Prince William and Kate Middleton! The royal duo celebrated 12 years of marriage on Saturday, April 29, and commemorated the milestone with a few romantic gifts and surprises.

Although the Prince and Princess of Wales typically choose to keep their anniversaries simple, this year they went above and beyond, US Weekly reports. An insider told the outlet that Prince William surprised Princess Kate with a family heirloom—a beautiful diamond ring that belonged to his late mother, Princess Diana—to mark the occasion.

But the surprises didn't end there: Prince William's next gift brought his wife right back to their 2011 royal wedding. "As a sweet gesture, [William] gave her a replica of the bouquet of flowers that she walked down the aisle holding on their wedding day—to symbolize their love, unity, and friendship," the source told Us Weekly.

Princess Kate chose to commemorate the couple's anniversary by paying homage their alma mater, the University of St. Andrews—where the royals first met. "Kate put her artistic skills to good use and surprised William [with] a framed sketch of the two of them from an old photograph taken during their St. Andrew's years," the source said. "He was blown away by it!"

The pair also marked their marriage milestone on social media, sharing a never-before-seen photo on their joint Instagram page.

The image, which was posted with the caption "12 years" followed by a heart emoji, was taken by photographer Matt Porteous last year. It features Prince William and Princess Kate riding bikes side by side in the Norfolk countryside—with their arms wrapped around each other (a rare sign of affection from this formal, private pair!).