Kate Middleton, William make surprise appearance as King Charles hits NY

On their 15th wedding anniversary, Princess Kate and her husband Prince William left fans in awe with their admirable gesture.

The future monarch and Catherine chose service with celebration, making a surprise visit to IntoUniversity that left fans inspired by their commitment to the next generation.

The much-loved royal couple's gesture was a touching tribute to the young people, and a subtle nod of support to King Charles and Queen Camilla, who are representing the Crown in the US.

Kensington Palace shared new photos of the Prince and Princess of Wales on their official Instagram account with a heartwarming message.

 "A 15th wedding anniversary drop-in to @intouniversity. A charity that aims to help young people reach their full potential in education and beyond."

The couple let their actions speak louder than words, championing the teens whose futures they’re shaping.

The post garnered massive likes and hearts from fans, with one wrote in comments section: "Wonderful engagement and Happy Wedding Anniversary again."

Another reacted: "Happy wedding anniversary to you both."

The third one wrote: "The most PERFECT engagement for their wedding anniversary."

The couple have marked their big day with visit to a location that holds a special place in Kate's heart. 

They were in Walworth, as they joined a group of Year 5 students from the Victory Primary School. They took part in one of the charity's programmes of free immersive educational activities and workshops.

The organisation was one of the 26 charities selected by William and Kate for Their Royal Highnesses' Royal Wedding Gift Fund.

This wasn't the only way that the couple marked their Crystal Anniversary, as they had lunch at The Goring following their outing.

The hotel has a special significance for Kate, as she stayed in the five-star hotel the night before her wedding to William.

Earlier, they released a gorgeous family portrait, featuring the couple and their children, Prince George, 12, Princess Charlotte, ten, and Prince Louis, eight.

The candid photo was taken during their holiday to Cornwall earlier this month by one of their most trusted photographers, Matt Porteous.