In a private family service, the coffin of Queen Elizabeth and her husband Prince Philip, who died last year, will be buried together.
More than 2,000 people, including royals from around the world and heads of state, will attend Queen Elizabeth's state funeral today- the "biggest-ever policing and protective operation" in the UK - costing over $7.5 million.
Here are the top 10 updates on this big story
1. About 10,000 police personnel will take part in the solemn procession to and from Westminster Abbey - the imposing location for royal coronations, marriages and funerals for more than 1,000 years. Hundreds of volunteer marshals and members of armed forces will also act as stewards along the processional route.
2. Presidents, prime ministers and royals will gather offsite before being taken by bus to the abbey - though an exception is being made for US President Joe Biden, who is expected to arrive in his armored limousine, known as The Beast.
3. Drones over central London have been temporarily banned, and Heathrow Airport is grounding scores of flights so that aircraft noise does not disturb the funeral service.
4. More than 22 miles of barriers have been deployed in central London to control the crowds.
5. Shortly before 11 am, Queen's coffin, covered in the Royal Standard flag with the Imperial State Crown on top, will be placed on a gun carriage and pulled by naval personnel to Westminster Abbey. The queen's eldest son and successor, King Charles III, will lead mourners, alongside his three siblings and his heir, Prince William.
6. The coffin will be then brought through central London, past the queen's Buckingham Palace home to the Wellington Arch at Hyde Park Corner, with the monarch and the royal family following again on foot during the 1.5 mile procession.
7. From there, it will be placed on a hearse to be driven to Windsor Castle in west London for a service at St George's Chapel. This will conclude with the Queen's crown, orb and sceptre - symbols of the monarch's power and governance - being removed from the coffin and placed on the altar.
8. The Lord Chamberlain, the most senior official in the royal household, will break his 'Wand of Office', signifying the end of his service to the sovereign, and place it on the casket.
9. It will then be lowered into the royal vault as the Sovereign's Piper plays a lament, slowly walking away until music in the chapel gradually fades.
10. Later in the evening, in a private family service, the coffin of Queen Elizabeth and her husband Prince Philip, who died last year, will be buried together at the King George VI Memorial Chapel, where her parents and sister, Princess Margaret, also rest.