The King’s Body Guard, formed of Gentlemen at Arms, Yeomen of the Guard and Scots Guards, change guard duties around the coffin of Queen Elizabeth II, lying in state inside Westminster Hall, on Sunday. Adrian Dennis/Pool Photo via AP

LONDON — Thousands of police, hundreds of British troops and an army of officials made final preparations Sunday for the state funeral of Queen Elizabeth II – a spectacular display of national mourning that will also be the biggest gathering of world leaders for years.

U.S. President Biden and first lady Jill Biden were among thousands of mourners – from locals and tourists to world leaders – to pay their respects at Westminster Hall, where the queen is lying in state. The president made the sign of the cross and put his hand to his heart as he stood quietly near the casket in the ornate 900-year-old hall.

Biden  also signed the official condolence book and attended a reception Sunday at Buckingham Palace hosted by King Charles III before going to the state funeral at Westminster Abbey on Monday. He is one of 500 world leaders and royals invited to the funeral, along with hundreds of British charity workers.

As the dignitaries poured in, the clock was ticking down for those seeking a place in the longest queue many have ever seen to file past the queen’s coffin as it lies in state at Westminster Hall. The miles-long queue is expected to be closed to new arrivals later Sunday so that everyone in line can view the coffin before Monday morning, when it will be taken to Westminster Abbey for the queen’s funeral.

Family by family, thousands of people kept lining up around the clock, braving chilly overnight temperatures and waits of up to 17 hours in a queue that stretched for over 5 miles.

Lauren Wilson, a 36-year-old student, was in the much shorter queue for people with mobility issues. She said she wanted to experience in person the coffin lying in state.

“The world is in such a weird place and then this happened. It feels more momentous,” she said.

She worried that the pageantry surrounding Elizabeth’s death deprives the queen’s relatives of the ability to come to terms with their loss.

“The family are not allowed to grieve. I find it quite heartbreaking,” she said.

The queen’s eight grandchildren, led by heir to the throne Prince William, circled the coffin and stood with their heads bowed during a silent vigil on Saturday evening.

Among the foreign leaders in London was New Zealand Prime Minister Jacinda Ardern, who told the BBC she was humbled to represent her nation at the funeral and to witness the national outpouring of grief and respect for the late queen.

“The thing that I will take away from this period is just the beauty of the public’s response, the kindness that you see from members of the public, the patience, the camaraderie. That has been, for me, the most moving tribute of all, has been the public response of the British people,” she said.

People across the U.K. will also pause Sunday evening for a nationwide minute of silence to remember the queen, who died Sept. 8 at 96 after 70 years on the throne. Monday has been declared a public holiday, and the funeral will be broadcast to a huge television audience worldwide and screened to crowds in parks and public spaces across the country.

Police officers from around the country will be on duty as part of the biggest one-day policing operation in London’s history.

Crowds also gathered Sunday near Windsor Castle, where the queen will be laid to rest at a private family ceremony on Monday evening.

“I think it’s been amazing,” said Anna Pettigrew, a 55-year-old teacher. “It’s been very emotional, and I think it’s been a very fitting tribute to a wonderful queen.”

Camilla, the new queen consort, paid tribute to the queen in a video message, saying the monarch “carved her own role” as a “solitary woman” on a world stage dominated by men.

“I will always remember her smile. That smile is unforgettable,” said Camilla, who is married to Charles.

Prince Andrew also paid tribute to his mother, saying he would forever treasure “your love for a son, your compassion, your care, your confidence.”

“I will miss your insights, advice and humor,” he said.

Andrew, the third of the queen’s four children, has been relieved of official royal duties and stripped of his honorary military titles over his friendship with the late sex offender Jeffrey Epstein.

After queen’s four children – Charles, Princess Anne, Andrew and Prince Edward – held a vigil Friday around her coffin, on Saturday night it was the grandchildren’s turn.

William and Prince Harry, Charles’ sons, were joined by Anne’s children, Zara Tindall and Peter Philips; Andrew’s daughters, Princess Beatrice and Princess Eugenie; and Edward’s two children – Lady Louise Windsor and James, Viscount Severn.

William stood with his head bowed at the head of the coffin and Harry at the foot. Both princes, who are military veterans, were in uniform. The crowd kept slowly, silently filing past.

“You could see that they were thinking hard about their grandmother, the queen,” said Ian Mockett, a civil engineer from Oxford in southern England. “It was good to see them all together as a set of grandchildren, given the things that have happened over the last few years.”

The silence in Westminster Hall was broken briefly Friday when a man lunged at the coffin. London police said Sunday that 28-year-old Muhammad Khan of London has been charged with behavior intended to “cause alarm, harassment or distress.” He has a court date Monday.

The lying-in-state continues until early Monday morning, when the queen’s coffin will be moved on a gun carriage pulled by 142 Royal Navy sailors to nearby Westminster Abbey for the funeral, the finale of 10 days of national mourning for Britain’s longest-reigning monarch.

After the service Monday at the abbey, the late queen’s coffin will be transported through the historic heart of London on the state gun carriage. It will then be taken in a hearse to Windsor, where the queen will be interred alongside her late husband, Prince Philip, who died last year at 99.