Many people from Northern Ireland are amongst those queuing for hours to pay their respects to Queen Elizabeth II.
At times the line stretches for more than four miles along the banks of the River Thames.
Among the visitors on Thursday was the mayor of Causeway Coast and Glens Borough Council in Northern Ireland.
Ivor Wallace, 60, 4am to catch a flight to London.
He queued for six hours to attend the Queen's lying-in-state at Westminster Hall, something he said was a "very emotional experience".
Mr Wallace added: "She was just always there and the person that everybody looked up to. She was a grandmother figure to most people."
The Mayor had also modified his gold chain, wrapping a black ribbon around it, with a black bow at the bottom.
“We feel very privileged to be in London at this time,” Suzanne Matthews told UTV.
Behind the scenes, young people from Northern Ireland are playing their part.
Nine local scouts were selected from hundreds to help usher the crowds.
“To be offered this opportunity is phenomenal and I’m just so happy to be here,” Nathan Quee from Bangor said.
“We’re managing what is called the ‘Disney Queue’ and we can fit around 8,000 people inside. We’re also taking donations towards the food banks and sorting through that and helping the stewards.
“I actually met the Queen at Hillsborough Castle and she was a lovely lady. She’s done so much for the people of Northern Ireland and the people of the UK – especially scouts. We make a promise within scouts to do our duty to the Queen and I feel that this is us doing our duty for her.”
The traditional colourful scout scarves has been replaced with black ones for those on duty.
“This is the funeral scarf of the Queen,” said Eve Barrett. “We’ve all been given these and I think we’re the first in the UK and I’m very honoured to be one of the few to have this scarf.”
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