We still remember when Prince George was dressed in blue, holding his daddy's hand as he arrived at Lindo Wing back in May 2015.
Three years later, this exciting moment is happening again.
This time Prince George and Princess Charlotte are meeting yet another royal baby -- their brand new baby brother.
The Duchess of Cambridge gave birth to her and Prince William's third child on Monday, April 23rd at 1101hrs.
Kensington Palace confirmed in a tweet that both mother and baby were doing well, and that Prince William was there for the birth.
All eyes and cameras stationed themselves outside the Paddington hospital to capture the family arriving to celebrate the milestone.
Just hours following the news, the new-dad-of three emerged from the prestigious facility to see Prince George and Princess Charlotte at Kensington Palace.
Smiling and waving in the direction of waiting media, the second-in-line to the throne said "back in a minute" as he made his way toward the driver's side of a waiting car.
Not long after, the royal arrived with George and Charlotte - and we can barely handle our emotions following their darling - albeit brief - appearance!
Big brother George appeared somewhat overwhelmed by the crowds and chose to stay close to his dad. The four-year-old was dressed in his school uniform made up of a navy V-neck jumper, a blue shirt, knee-length shorts and shiny black shoes.
Meanwhile, Charlotte - who will turn three next month - appeared confident as she trotted toward the hospital even stopping to glance back and wave at the masses of waiting media. She was princess perfection in a blue floral dress, navy cardigan and perfectly-coordinated leather buckle shoes.
The young family did not stop to pose for photographs.
Kate and William's third child is fifth in the line of Succession after His Royal Highness The Prince of Wales, His Royal Highness The Duke of Cambridge, His Royal Highness Prince George of Cambridge and Her Royal Highness Princess Charlotte of Cambridge.
Kensington Palace confirmed the Duchess was in labour at 08:23am in the morning, London time via Twitter in a statement which read: "Her Royal Highness The Duchess of Cambridge was admitted to St. Mary's Hospital, Paddington, London earlier this morning in the early stages of labour."
"The Duchess travelled by car from Kensington Palace to the Lindo Wing at St. Mary's Hospital with The Duke of Cambridge."
Royals, fans and celebrities have been quick to share their congratulations to Prince William and Duchess Catherine for their new son.
Kensington Palace shared, "The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, Prince Harry and members of both families have been informed and are delighted with the news."