Queen Elizabeth II

Windsor Castle, home to the British monarchy for hundreds of years, was built by William the Conqueror in the 1070s, according to the monarchy's official website. W. Buss/De Agostini/Getty Images hide caption

Queen Elizabeth II. Kirsty Wigglesworth/AP hide caption

Stuntman Mark Sutton, doubling for actor Daniel Craig (or, as James Bond) during the Opening Ceremony of the London Olympics last summer. Ian Langsdon/EPA /LANDOV hide caption

Britain's Queen Elizabeth II (second left) stands with West German Chancellor Helmut Kohl (left), U.S. President Ronald Reagan and Britain's Prime Minister Margaret Thatcher at London's Buckingham Palace on June 10, 1984. AP hide caption

Little Princess Elizabeth takes a ride on the grounds of Windsor Castle in 1927 with her cousin, Gerald Lascelles. AP hide caption

Barnes and Noble CEO William J. Lynch, Jr. displays a Nook reader in 2010. Michael Nagle/Getty Images hide caption

Britain's Queen Elizabeth II will sign a new charter for the 54-member Commonwealth on Monday. Ian Gavan/AFP/Getty Images hide caption

Britain's Queen Elizabeth II as she left King Edward VII hospital in London on Monday. Bogdan Maran/EPA /LANDOV hide caption

Britain's Queen Elizabeth II has been taken Sunday to a hospital in central London. She's being treated for symptoms of gastroenteritis. Matt Dunham/AP hide caption

Queen Elizabeth II wears 3-D glasses during a visit to the University of Sheffield, in 2010. This year, the queen's annual Christmas message will broadcast in 3-D. WPA Pool/Getty Images hide caption

The British cleric Abu-Hamza al Masri, seen here in February 2003, is set to be extradited to the United States to face terrorism charges linked to the taking of 16 hostages in Yemen in 1998 and setting up a terrorist training camp in rural Oregon. Odd Andersen/AFP/Getty Images hide caption

Queen Elizabeth II shook hands with Deputy First Minister of Northern Ireland Martin McGuinness today in Belfast. McGuinness is a former senior member of the IRA. Paul Faith/WPA Pool/Getty Images hide caption

Queen Elizabeth II, as she rode toward Buckingham Palace earlier today. The Duchess of Cornwall (Camilla) rode beside her. Also in the carriage: the Prince of Wales (Charles). Sean Gallup/Getty Images hide caption

On Saturday, Prince Philip was at the second day of the Epsom Derby horse racing festival. Adrian Dennis/AFP/Getty Images hide caption

Queen Elizabeth II sailed down the River Thames on Sunday amid a motley but majestic flotilla of 1,000 vessels, mustered to mark her 60 years on the British throne. Matt Cardy/Getty Images hide caption