Happy 90th Birthday, Queen Elizabeth II!

Posted at 7:42 AM, Apr 21, 2016
and last updated 2016-04-21 07:45:11-04

LONDON – The longest-reigning British monarch in history, Queen Elizabeth II, turns 90-years-old on Thursday.

Last year, the Queen gained the title of Britain’s longest-ever reigning monarch.  The Queen ascended the throne 64 years ago, after the death of her father, King George VI.

On Thursday, she achieved another milestone as the nation’s first sovereign to celebrate her 90th birthday.

She’ll be spending her 90th birthday at Windsor Castle, the oldest and largest occupied castle in the world. She plans to mark the day with a walkabout near her main residence in Windsor, before lighting a beacon relay in the evening.

ater in the summer, formal celebrations will be held to mark her “official birthday,” culminating with a national service of Thanksgiving at St. Paul’s Cathedral and a giant picnic outside Buckingham Palace for 10,000 guests.

On Wednesday, the monarch’s celebrations began with another first: an official photograph of four generations of royals, featuring three future kings posing at Buckingham Palace. The image of the Queen, and Princes Charles, William and George will be on special stamps issued to mark the Queen’s life.

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The Queen surrounded by her two youngest grandchildren and her five great-grandchildren #Queenat90 This is the first in a series of official photographs released today to mark The Queen's 90th birthday. They were taken at Windsor Castle just after Easter by renowned portrait photographer Annie Leibovitz. From left: James, Viscount Severn, Lady Louise, Mia Tindell, Queen Elizabeth, Princess Charlotte, Savannah Phillips, Prince George and Isla Phillips.

A post shared by The Royal Family (@theroyalfamily) on

It’s a milestone for 2-year-old Prince George, who makes his “stamp” debut, his first of many to come, pictured standing on a stack of blocks for a boost.

Despite being one of the most famous public figures in the world, not much is known about Queen Elizabeth on a personal level. She has never given an interview to the media and never written an autobiography. It’s known that she likes horses, corgis and the outdoors.  We know also that she’s a deeply religious person and has a sense of humor. But we know nothing about her politics or her views on anything remotely controversial.

The Queen has been married to 94-year-old Prince Philip, Duke of Edinburgh since 1947. They have four children (Prince Charles, Princess Anne, Prince Andrew, Prince Edward), eight grandchildren (William, Duke of Cambridge; Prince Harry of Wales; Peter Phillips; Zara Tindall; Princess Beatrice of York; Princess Eugenie of York; Lady Louise of Windsor; James, Viscount Severn) and five great-grandchildren (Prince George of Cambridge; Princess Charlotte of Cambridge; Savannah; Isla; Mia Grace).

This story was written with assistance from the CNN Wire.