In Photos, Queen Elizabeth II's funeral: Unprecedented security and preparation as world leaders head to the UK

Huge crowds built in central London overnight and from early morning on Monday to secure a spot to watch the state funeral of Queen Elizabeth II at Westminster Abbey. As dawn broke over the River Thames, a steady stream of well-wishers streamed out of Embankment underground station headed for Parliament Square.

The coffin of Queen Elizabeth II leaves Westminster Hall for her funeral service in Westminster Abbey in central London.

The coffin of Queen Elizabeth II is placed on a gun carriage during her funeral service in Westminster Abbey in central London.

Britain's Prince William, Prince of Wales (L) and Britain's Prince Harry (C), Duke of Sussex arrive at Westminster Abbey in London on September 19, 2022, for the State Funeral Service for Britain's Queen Elizabeth II.

Police officers take positions near The Sanctuary, before the coffin of Queen Elizabeth II is carried into Westminster Abbey for her funeral in central London.

Dignitaries arrive with many heads of state by bus to the Abbey. Westminster Abbey is where Elizabeth was married in 1947 and crowned in 1953.

VIPs are checked by security as they arrive at the State funeral, held at Westminster Abbey.

Crowd wait near Horseguards Parade at the state funeral in London.

Police officers march up the Mall in central London. The Queen, who died aged 96 on Sept. 8, will be buried at Windsor alongside her late husband, Prince Philip, who died last year.

Soldiers in ceremonial uniform walk into Westminster Abbey. Mourners are arriving at Westminster Abbey to take their seats for Queen Elizabeth II's state funeral service.

A Yeomen of the Guard, right, and Gentlemen at Arms members take positions ahead of the funeral in central London.

Guests and officials begin to take their places prior to the coffin of Queen Elizabeth II being carried into Westminster Abbey for her funeral in central London.

Funeral programs are left on chairs on the day of Britain's Queen Elizabeth II's State Funeral at Westminster Abbey in London.

Spectators line the Long Walk at Windsor Castle ahead of the state funeral of Queen Elizabeth II, in Windsor, UK, on Monday, Sept. 19, 2022. The Queen's life is commemorated at her state funeral in Westminster Abbey in London, to be attended by roughly 500 global dignitaries and world leaders including US President Joe Biden.