The Duke and Duchess of Cambridge experienced a historic day on Thursday, not only did they celebrate the Queen's 70 years on the throne, but their three children, Prince George, Princess Charlotte and Prince Louis made their carriage debut at Trooping the Colour.
MORE: The Queen pulls out of Friday's Jubilee celebrations due to 'discomfort'
It was a first for the three, and they rode alongside their mother, Kate, who donned a beautiful white coat dress from Alexander McQueen and a Philip Treacy hat, and the Duchess of Cornwall, who looked elegant in a baby blue ensemble.
WATCH: Princess Charlotte has cheeky moment with little brother Prince Louis
As the day come to an end, the royal couple took to Instagram to share their thoughts on the big day.
READ: Kate Middleton and her children George, Charlotte and Louis bow their heads at Trooping the Colour
RELATED: Prince Louis had the sweetest unseen moment after Trooping the Colour carriage debut
"Day one of the #PlatinumJubilee. It's been lovely to see so many of you out today and see how you're already enjoying this weekend, celebrating Her Majesty The Queen," they wrote alongside a picture the Tree of Trees, which stands 70 ft. tall in honour of the Queen outside Buckingham Palace.
The Cambridge kids made their carriage debut on Thursday
Before their social media message was shared, Prince William joined the Queen, although separated by 22 miles, in the beacon lighting ceremony.
Speaking about Trooping, Prince William revealed it was "pretty impressive" and "a big day".
William was speaking to Mike Bloomberg, Sponsor of Tree of Trees, and said: "It was a big day today, pretty impressive. Did you see the flypast?".
The Duke watched on a screen as the Queen ceremonially lit the Principal Beacon from Windsor Castle.
The lights illuminated the Tree of Trees outside the palace and he heard Gregory Porter perform the official Beacons song called A Life Lived With Grace.
William attended a special ceremony for the lighting of the Principal Beacon at Buckingham Palace
Just hours before the rare night engagement, Buckingham Palace released a statement revealed that the Queen will be unable to attend Friday's Jubilee service.
It stated that Her Majesty "greatly enjoyed" her birthday celebration and the flypast in London during the Trooping the Colour parade.
However, she did "experience some discomfort," due to which she will be pulling out of Friday's national thanksgiving service.
"Taking into account the journey and activity required to participate in tomorrow's National Service of Thanksgiving at St Paul's Cathedral, Her Majesty, with great reluctance, has concluded that she will not attend," the statement read.