Britain's Queen Elizabeth died of old age, according to her death certificate, which has been published by the National Records of Scotland.
The country's longest-reigning monarch died peacefully, at the age of 96, at Balmoral Castle, her summer home in the Scottish Highlands, on September 8.
And the certificate recorded her time of death as 3:10pm — three hours before her death was publicly announced.
The Queen had carried out her last official duty of appointing Liz Truss as Britain's new prime minister just two days earlier.
Buckingham Palace had released a statement just after 12:30pm on September 8 to say doctors were concerned about the Queen's health and that she would remain under medical supervision.
Her death was officially announced at 6:30pm.
The Queen, who spent 70 years on the throne, had been suffering from what Buckingham Palace had called "episodic mobility problems" since the end of last year, forcing her to withdraw from nearly all her public engagements.
Her certificate of death was registered by her daughter, Anne, The Princess Royal, on September 16.
Mourners queue as Windsor Castle reopens to visitors
While other royal residences — inlcuding the Queen's Gallery at Buckingham Palace and the Palace of Holyroodhouse — reopened to visitors last week, Windsor Castle only reopened on Thursday.
The Queen was buried there, inside the King George VI Memorial Chapel, which is part of St George's Chapel on the grounds of Windsor Castle.
Hundreds of people lined up outside Windsor Castle to pay their final respects the Queen on Thursday morning.
Among the early arrivals was Anne Daley, 65, from Cardiff, who got to the castle at 7:30am, well ahead of the 10am opening time.
Ms Daley said she was also one of the first in line as tens of thousands of people shuffled through Westminster Hall to view the Queen lying in state before her funeral earlier this month.
She said she felt emotional thinking about the death of the Queen and her husband, Prince Philip, who died last year.
"The castle feels like empty, gloomy," Ms Daley said.
"Nobody's living in it. You know, you've lost the Queen, you've lost the Duke, you's lost the corgis.
"It's like when you've sold your house and all the history is gone."
People have to buy a ticket to Windsor Castle to visit the chapel.
The price for adults is 26.50 pounds ($45.35) Sunday through Friday, and 28.50 pounds on Saturdays.
Visitors not allowed to bring flowers into castle
In the days after Queen's death, floral tributes were laid at sites connected to the royal family throughout the UK, but the Royal Collection Trust website says visitors won't be allowed to bring flowers into Windsor Castle.
Instead, it directs people to a designated floral tribute area outside Windsor Castle, about a five-minute walk from the visitor entrance.
St George's Chapel is open to visitors every day except Sunday, when it's only open to people attending a service there.
The Queen's tomb is marked by a slab of hand-carved Belgian black marble.
Her name is inscribed on the ledger stone in inlaid brass lettering, alongside the names of her husband, mother and father.
The coffins of the Queen and Prince Philip were interred together during a private family service at the chapel following the state funeral on September 19.
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