Queen Elizabeth's official birthday was marked with the annual Trooping the Colour ceremony on Saturday. /VCG Photo

The Queen was joined by members of royal family and thousands of spectators to watch the parade during the ceremony. /VCG Photo

The Royal Air Force also made a flypast as part of the ceremony. /VCG Photo  

Trooping the Colour is a military tradition, which dates back to the early 18th century. The annual event usually features hundreds of officers, horses and musicians from the Household Division in ceremonial uniform. /VCG Photo

It is now a celebratory parade in honor of the Queen's official birthday, which has taken place in the second Saturday in June since 1959. The actual day she was born is April 21. /VCG Photo