A three-year-old Princess Elizabeth is seen on the cover of Time magazine in April 1929. (Public domain)

Princess Elizabeth and her sister, Princess Margaret, pull a steam whistle on a train during a visit to South Africa in 1947. (Public domain)

rincess Elizabeth, then 19 years old, in the Auxiliary Territorial Service uniform near the close of World War II in April 1945. (Public domain)

Queen Elizabeth II and her husband, Prince Phillip, in her 1953 coronation photo. (Public domain)

Queen Elizabeth II and her children meet with former United Kingdom Prime Minister Winston Churchill in 1957. (UK government photo)

Formal portrait of Queen Elizabeth II, 1959

Queen Elizabeth II and U.S. President Ronald Reagan riding horses at Windsor Castle in 1982. (Public domain)

Queen Elizabeth II at her 2002 Golden Jubilee dinner with then-British prime minister Tony Blair and former prime ministers, all of whom served during her reign. From left, Blair, Margaret Thatcher, Edward Heath, Elizabeth, James Callaghan and John Major. (United Kingdom government photo)

U.S. President Barack Obama and first lady Michelle Obama meet with Queen Elizabeth II at Buckingham Palace in 2009. (White House photo)

Queen Elizabeth II is seen during a 2015 visit to the HMS Ocean in Devonport at a ceremony to rededicate the ship. (Joel Rouse/ UK Ministry of Defence)