Queen Elizabeth turns 96, celebrates birthday in Sandringham

Queen Elizabeth II celebrated her 96th birthday on Thursday, in the same year that marks her 70 years on the throne.

The longest-reigning monarch traveled to Sandringham, her estate in Norfolk, for a private break.

 The palace has released a stunning portrait to mark the Queen's big day, showing the monarch standing between two fell ponies named Bybeck Nightingale and Bybeck Katie.

The photo was taken in the grounds of Windsor Castle in March, according to the royal family Twitter account.

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, it's particularly special to be celebrating in this #PlatinumJubilee year."

Charles, the Prince of Wales and Camilla, Duchess of Cornwall also sent a birthday message to the Queen.

"Wishing Her Majesty The Queen a particularly special 96th birthday today, as we celebrate her Platinum Jubilee year," the pair posted on Twitter.

The Platinum Jubilee marks seven decades since the Queen ascended to the throne in 1952, making her both the longest-reigning British monarch and the longest-serving female head of state in history.