London, UK - US President Joe Biden has said the "world is better'' because of Queen Elizabeth II as he offered his condolences to the British people for their loss.

Biden was speaking at Lancaster House after visiting Westminster Hall to pay his respects to the late monarch.

The president arrived with his wife Jill at the lying in state shortly before 5:00 PM on Sunday, ahead of his attendance at Monday's funeral.

They were joined by the US ambassador to the UK, Jane Hartley. The president stood on the platform for around two minutes, taking in the scene, where he crossed himself and exchanged a few words with the first lady.

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He looked on with a somber expression and put his hand to his heart before walking away.

Large crowds were gathered behind barricades near Buckingham Palace and Parliament Square Garden ready to take photos of the motorcade as it glided into the Palace of Westminster.

Some children were sitting on their parents' shoulders trying to get a view.

Security was tight and road crossings were closed ahead of the visit as rumors spread through the crowd about the imminent arrival of the president and his entourage.

The Bidens were greeted at Westminster Hall by Black Rod Sarah Clarke. They then traveled to Lancaster House, where Biden and his wife signed the book of condolence.

Speaking at Lancaster House, Biden said: "To all the people of England, all the people of the United Kingdom, our hearts go out to you. You were fortunate to have had her for 70 years, we all were. The world is better for her."

He also had some words for the Queen's son, King Charles III: "It’s a loss that leaves a giant hole and sometimes you think you'll never, you’ll never overcome it. But, as I’ve told the King, she’s gonna be with him every step of the way, every minute, every moment, and a reassuring notion."