To celebrate the regal birth, monuments on both sides of the Atlantic lit up in blue that evening as a tribute to the newest member of the royal family.
Check out the festive photos below!
Both the US and Canadian sides of Niagra Falls were lit in blue to announce the birth to visitors.
The London Eye was lit in the colors of the Union Jack to celebrate the royal addition.
Toronto's CN Tower got into the imperial spirit.
In Ontario, the Peace Tower and Parliament buildings joined in on the fun.
London's Trafalgar Square fountains were an awe-inspiring shade of blue.
Click over to the Daily Mail to see more photos.