Queen Elizabeth arrives for 90th birthday celebrations

Britain's Queen Elizabeth arrives at Windsor Castle for her 90th birthday celebrations.

LONDON, UNITED KINGDOM (Reuters) - Britain's Queen Elizabeth arrived at the grounds of Windsor Castle to attend a celebration of her 90th birthday on Sunday (May 15).

The celebrations featured some of the leading stars of show business and almost 1,000 horses.

The pageant on the grounds of her Windsor Castle residence near London was shown live on broadcaster ITV.

The Queen has been on the throne for 64 years and is the oldest monarch in British history.

Sunday's concert is the highlight of a four-day pageant at Windsor which also includes equestrian displays involving around 900 horses ridden by riders from around the world to mark the queen's passion for the animals.