Leading politicians will meet in the UK's parliaments and assemblies later to pay tribute to the Duke of Edinburgh - in person and via video link.
The House of Commons, the Scottish Parliament and the Senedd are being recalled especially.
The Northern Ireland Assembly and the House of Lords will also devote Monday to marking the life of Prince Philip, who died on Friday, aged 99.
The commemorations take place ahead of the duke's funeral on Saturday.
On Sunday, the Duke of York said the Queen described the death of her husband of 73 years as "having left a huge void in her life".
Prince Andrew said his father's death was a "terrible loss", and his family was "rallying round" to help the Queen.
The Princess Royal, meanwhile, described her father as her "teacher, supporter and critic".
Princess Anne - the duke's only daughter - said he would leave a "legacy which can inspire us all".
In a statement on the Royal Family's website, the princess said she "most wanted to emulate" her father's example of a "life well lived and service freely given".
She said "his ability to treat every person as an individual in their own right with their own skills" was reflected in the organisations he worked with.
"I regard it as an honour and a privilege to have been asked to follow in his footsteps and it has been a pleasure to have kept him in touch with their activities," she added.
The House of Commons, which was supposed to be on its Easter break until Tuesday, is being recalled a day early, with MPs giving their tributes to the duke from 14:30 BST.
The House of Lords, which had already been due to sit on Monday, will take part in a minute's silence at 13:00 before peers give their tributes. The day's scheduled business will be put back to Wednesday.
The Scottish Parliament and Sennedd, both of which were not due to be sitting ahead of May's elections, will be recalled for members to pay tribute from 11:00.
And the Northern Ireland Assembly will meet from 12:00.
The tributes come during a period of national mourning which will end on the day of Prince Philip's funeral at Windsor Castle's St George's Chapel.
A national minute's silence will be held to coincide with the start of the service at 15:00.
The Duke of Sussex will attend the service, without his wife, the Duchess of Sussex, who is pregnant and will remain at home in California on the advice of doctors.
Members of the Royal Family will walk behind the coffin ahead of the funeral.