Queen Elizabeth II Castle

Queen Elizabeth II celebrates her 89th birthdayGetty

The Queen is celebrating her 89th birthday privately today (21 April) at Windsor Castle.

To mark her special day, the King's Troop Royal Horse Artillery will fire a 41-gun royal salute at midday in Hyde Park, followed by music from the Band of the Royal Artillery.

The Honourable Artillery Company will also stage a 62-gun royal salute from the riverside at the Tower of London overlooking HMS Belfast. There will also be royal salutes at Edinburgh Castle, Cardiff Castle, and Hillsborough Castle in County Down.

The Queen was born Elizabeth Alexandra Mary Windsor of York on 21 April, at 2.40am in 1926, at her mother's parents' Mayfair home. But she also has an official birthday on a Saturday in June marked by the Trooping the Colour ceremony. Monarchs born in the winter traditionally are given two birthdays so they can celebrate when the weather is more suitable to mark the occasion.

Top 10 facts about the Queen

1. She paid for her wedding dress using clothing ration coupons.
2. Twelve prime ministers have served under her.
3. The Queen is fluent in French.
4. She delivers a Christmas message to her subjects every year. She missed it only once, in 1969.
5. The Queen technically owns the whales and dolphins in the UK waters.
6. She drinks a cup of tea every day at 7.30am.
7. Artists have painted about 130 official portraits of her.
8. Her 1953 coronation was the first to be televised.
9. She's had more than 30 corgis during her reign.