Trooping the Colour: Behind the scenes with cavalry soldiers
14 June 2014 Last updated at 08:58 BST
In a tradition that started in the 18th century, Britain is celebrating the Queen's official birthday in London.
The men and horses of the Household Cavalry will ride to Horse Guard's Parade to salute her.
Roya Nikkhah was given exclusive access to the cavalry barracks at Hyde Park.