Mourners from all four nations of the UK are paying their respects to the Queen after the death of the longest-serving British monarch.
King Charles addressed the nation at 6pm, with more than 2,000 members of the public listening in as a service of prayer and reflection was held at St Paul's Cathedral.
Prime Minister Liz Truss also led MPs past and present in paying tribute to Her Majesty at the House of Commons this afternoon.
Flags at royal residences were placed at half-mast on Thursday and will remain so until 8am on the final day of mourning, a sentiment echoed at many public and government buildings.
Here, Sky News looks at what is being done to honour the Queen across the UK.
Royal gun salutes were fired at Hyde Park, the Tower of London and Stonehenge at 1pm on Friday, with one round fired for every year of the Queen's 96-year life.
There will be no physical books for mourners to write in at any royal residences - with an online version on the official Royal Family and Church of England websites.
However, visitors can sign condolence books at cathedrals in Guildford, Wakefield and Birmingham, where Sky's Lisa Dowd spoke to visitors.
Jacqui Francis, 60, was the first person to sign a book of condolence at the city's Hall of Memory.
"I came on behalf of my mother who is originally from Jamaica and lives in America now," she said.
"She would have been first in the queue as the Queen was part of the backdrop to her life.
"I came for myself to offer my condolences as the country mourns. The Queen is baked into this country, the money, the stamps, it will all change, what an iconic reign."
An exhibition of images showing the Queen's visits to the region will also be on display at Birmingham Library.
At a wreath laying ceremony, the mayor of the West Midlands and former managing director of John Lewis, Andy Street, recalled meeting the Queen.
"What struck me, when I was running John Lewis, she knew so much about the business, she was so utterly fixed on that and that was her incredible character: to connect. More widely, she somehow brought everyone together, and that unity will be most cherished," he told Sky News.
Authorities in Portsmouth, Derby, Preston, Nottingham, Lancashire, and Leeds are also among those which have set up books of condolence for residents to sign.
Thousands of bouquets, personal notes and candles have been left at the Queen's homes, including Sandringham.
Two-year-old Phoenix Child was among the crowds in Norfolk, clutching a Paddington toy as he laid a bunch of flowers, assisted by his grandmother, Dolores McKenna.
Meanwhile, Hillary-Fay Mellor, who placed a bouquet, said the Queen was the same age as her own mother, describing her as a "strong, devoted sovereign" and the "glue that held people together".
Mourners have also been laying flowers at the foot of a golden beech tree planted in 2002 by the Queen at the National Memorial Arboretum, home to the Armed Forces Memorial, in Staffordshire.
"This was a very special place for her, she came here on several occasions and is very much a place where people wish to come, reflect and remember Her Majesty," arboretum lead, Mark Ellis said.
Civic buildings will be bathed in purple light in Bristol and Leeds - where church bells chimed at lunchtime.
Meanwhile, in Manchester, advertising boards have been replaced with tributes to the Queen.
Thousands gathered in the pouring rain inside the grounds of Cardiff Castle for the 96-shot gun salute, fired by the 104 Regiment (Newport) of the Royal Artillery.
Sky's Dan Whitehead met people among the crowds, including Welsh sisters Jennifer Thomas, Janice Hughes and Jaqueline McCall.
They remember Her Majesty's coronation.
"I was heartbroken. I had such admiration for her, I thought she was a wonderful person who lived up to her word," Jennifer said.
Janice met the Queen when she visited the small Welsh mining village of Aberfan, following the coal tip disaster that killed 116 children and 28 adults in 1966.
"I remember seeing her getting out of the car and thinking how small and pretty she was," she said.
"I am devastated. It's a sad time and an end of an era."
The lord mayor of Cardiff was among leaders who opened a condolence book at the city hall this afternoon, with floral tributes laid on the lawn either side of the main entrance.
Several hundred people collected at the gates of Balmoral, but there wasn't a noise to match their number, Sky News' James Matthews reports.
This was an assembly to show respect and gratitude, quietly. Theirs was a solemnity and sorrow without, necessarily, any sense of shock.
They travelled from near and far, many to lay tributes in flower at the gates of the royal estate.
"Thank you Your Majesty our gracious lady," was written on one card, while another read "Many thanks for your love and devotion to our country."
Elsewhere, two-year-old Elizabeth Ewan, who was named after the Queen, left flowers at the Palace of Holyrood House in Edinburgh.
Her father, Samuel Ewan, said: "This is Elizabeth, she's named after her granny and after our Queen."
He said he was "very sad" but "also really grateful for the last 70 years".
Sky News correspondent Adele Robinson spoke to the Reverend Ruth Halley at Greyfriars Kirk, in the heart of the Scottish capital, where the public have been invited to take a quiet moment of reflection.
The church had a "steady stream" of visitors signing a book of condolences on Friday, with one message praising the Queen's "grace, compassion, and understanding" and thanking her for her "life of service lived fully".
The security screening required to approach the royal residence in Northern Ireland did not deter people from paying their respects, Sky News' David Blevins reports.
Men, women, and children came to leave flowers at the gates of Hillsborough Castle at Royal Hillsborough in County Down.
Fighting back tears, one woman said: "What a woman she was. What a life she had. It's so, so sad.
"It doesn't matter what religion you are, what colour you are, millions of people around the world are in the same state as me today."
One man and his daughter, grieving the recent passing of their own mother and grandmother, said: "We feel like we've lost another member of the family."
Several commented on the significant contribution the Queen made to efforts for a lasting peace in Northern Ireland.
"The bond between Britain and Ireland has been rough," one man said, "but she had her part to play."
Flowers were also placed at the Queen Elizabeth mural in Belfast, with a gun salute taking place at Hillsborough Castle in the city.