Britain’s four-day public holiday begins with a Trooping the Colour in celebration of Queen Elizabeth II’s Platinum Jubilee.

People gather along The Mall for the Queen’s Platinum Jubilee celebrations in London.

People gather at The Mall during the Queen’s Platinum Jubilee celebrations in London.

Members of Band of the Household Cavalry take part in the Queen’s Birthday Parade

The Queen’s guards march during the Trooping the Colour parade at Horse Guards.

Irish Wolf Hound “Turlough Mor” (a.k.a. Seamus), regimental mascot of the Irish Guards

The Kings troop of the royal horse artillery ride down the Mall on their way to fire ceremonial guns.

Britain’s Catherine, Duchess of Cambridge, Camilla, Duchess of Cornwall, Princess Charlotte, Prince George and Prince Louis

Queen Elizabeth II smiles as she watches from the balcony of Buckingham Palace