The Queen has traveled to Sandringham, her estate in Norfolk, eastern England, for a private break, Buckingham Palace told CNN. 

A portrait released to mark the occasion shows the monarch standing between two fell ponies named Bybeck Nightingale and Bybeck Katie. 

William and Catherine, the Duke and Duchess of Cambridge, sent the Queen a birthday message on social media. 

"Wishing Her Majesty The Queen a very happy 96th birthday today!" reads the tweet. "An inspiration to so many across the UK, the Commonwealth and the world 

To celebrate the unprecedented anniversary, a number of events will take place throughout the UK over the year