The coffin has been laying in state at St. Giles' Cathedral in the Scottish capital, before it is taken to London later on Tuesday.
Thousands of people lined up through the night in the Scottish capital Edinburgh, to pay their last respects to Queen Elizabeth II, whose coffin is lying in state at the city's St. Giles' Cathedral.
Mourners filed past slowly, some bowing their heads, as four members of the Royal Company of Archers stood vigil over the late monarch's flag-draped coffin.
The archers - who act as the British sovereign's bodyguard in Scotland, and whose company dates back to 1676 - are wearing hats called “Balmoral bonnets” adorned with a single eagle feather. Each of them is holding a wooden bow and a quiver of arrows.
Earlier they were joined by the Queen's four children: King Charles III, Princess Anne and Princes Andrew and Edward, who stood guard silently beside their mother's coffin which has the Crown of Scotland resting on a cushion on top.
The Scottish government is warning that the line, and waiting times, are expected to be long, with perhaps hours of standing. Visitors can leave the line to use toilet facilities. Authorities have introduced airport-style security at the 12th-century cathedral, banning people from taking inside the cathedral any large bags, sharp items, or food or liquids.
Earlier on Monday, the UK's new monarch King Charles III accompanied his late mother's coffin in a procession through the Scottish capital. Ceremonies and a church service highlighted the Queen's connection to Scotland, with a psalm sung in Gaelic, and a lone bagpiper playing a lament.
The Queen's coffin is to lie in state in the Scottish capital for 24 hours, after which it will travel to London and lie in state at the Palace of Westminster from Wednesday afternoon until the morning of the funeral on 19 September.
The coffin was originally planned to be transported on the Royal Train but will now be flown instead.
Parliament ceremonies in London
On Monday, before travelling north to Scotland, King Charles addressed the UK's two houses of parliament in London.
Citing the “selfless” example of his late mother, Queen Elizabeth II -- who died at Balmoral, Scotland, last Thursday, at the age of 96 -- Charles pledged to follow her lead and uphold Britain’s “vital parliamentary traditions”.
He lauded parliament as the “living and breathing instrument of our democracy”, and nodded to Shakespeare’s Henry VIII by calling his predecessor a “pattern to all princes living”.
Charles, 73, has succeeded Elizabeth II as Britain’s monarch, with his wife, Camilla, 75, joining him as Queen Consort.
The couple sat on ceremonial chairs in Westminster Hall, with cavalry troopers in red tunics and plumed helmets standing to attention behind.
Charles said: "While very young, Her late Majesty pledged herself to serve her country and her people and to maintain the precious principles of constitutional government which lie at the heart of our nation. This vow she kept with unsurpassed devotion."
Among the country’s MPs and peers was newly appointed Conservative prime minister, Liz Truss.
The Lords Speaker, former Labour MP John McFall, and Commons Speaker Lindsay Hoyle, both offered their condolences. The former commended Elizabeth as having been “a leader to, and a servant of, her people”, while the latter stated that people would lament “her loss … around the world”.
At the end of the ceremony, the lawmakers present stood up to sing the national anthem, “God Save The King”.
Queen Elizabeth II was Britain’s longest-serving monarch, having ascended the throne 70 years ago. Throughout her reign, she witnessed 15 prime ministers and some of the UK’s most important political moments, including the Falklands War, the Good Friday Agreement and the Brexit referendum.