Jacquelyn Martin/AP Photo
  • President Barack Obama meets with Britain's Prince William in the Oval Office of the White House in Washington, Dec. 8, 2014.
    Jacquelyn Martin/AP Photo
  • Prince Harry stands with First Lady Michelle Obama during an event to honor military families at the White House, May 9, 2013 in Washington, DC.
    Mark Wilson/Getty Images
  • President Barack Obama, right, speaks with Britain's Prince Charles prior to meetings in the Oval Office of the White House in Washington, DC, May 4, 2011.
    Saul Loeb/AFP/Getty Images
  • Prince Charles, right, and Camilla, Duchess of Cornwall pose with President George W. Bush and First Lady Laura Bush at a White House event, Nov. 2, 2005 in Washington DC.
    Tim Graham/Getty Images
  • Queen Elizabeth and Prince Philip, arrive at formal dinner hosted by First Lady Laura Bush and President George W. Bush at the White House, May 7, 2007 in Washington, DC.
    Chris Jackson/Getty Images
  • Princess Diana, left, attends the Hyde Centre Breakfast at the White House with First Lady Hilary Clinton, Sept. 24, 1996, in Washington, DC.
    Julian Parker/UK Press via Getty Images
  • Queen Elizabeth and Prince Philip attend a White House event hosted by First Lady Barbara Bush and President George H.W. Bush, Washington, DC, May 14, 1991.
    Tim Graham/Getty Images
  • Princess Diana and First Lady Barbara Bush speak before an event at the White House, Oct. 1, 1990.
    Jayne Fincher/Princess Diana Archive/Getty Images
  • Princess Diana dances with John Travolta at a White House event, Nov. 9, 1985.
    Anwar Hussein/Getty Images
  • President Ronald Reagan and First Lady Nancy Reagan welcome Prince Charles and his new bride, Princess Diana, to the White House, Washington, D.C., Nov. 9, 1985.
    Don Rypka/AFP/Getty Images
  • President Gerald Ford dances with Britain's Queen Elizabeth during a White House state dinner honoring the Queen US Bicentennial visit to Washington DC, July 7, 1976.
    Dirck Halstead/The LIFE Images Collection/Getty Images)
  • Prince Charles addresses an audience at the White House, as Princess Anne, right, and President Richard Nixon, center, look on, July 18, 1970.
    Gamma-Keystone via Getty Images
  • Queen Elizabeth and Prince Phillip attend a White House event with President Dwight D. Eisenhower and First Lady Mamie Eisenhower, Oct. 1, 1957, in Washington, DC.
    Gamma-Keystone via Getty Images
  • Prince Edward, the Duke of Windsor and his wife, Wallis Simpson, center, arrive in Washington, DC, June 24, 1942. Upon their arrival, they lunched at the White House as guests of President and Mrs. Roosevelt.
    Planet News Archive/SSPL/Getty Images
  • First Lady Eleanor Roosevelt, right, and Queen Elizabeth greet well wishers in Washington, DC, as they drive to the White House, Jan. 1, 1939.
    Underwood Archives/Getty Images