The Queen will celebrate her 80th birthday this week with a black tie dinner, a traditional royal walkabout and a church service.
A mixture of private and public celebrations are being staged to mark the historic occasion.
The Queen reaches the milestone age on Friday, April 21, but will also commemorate her official birthday later in the year on June 17.
On Friday, the Prince of Wales is hosting a formal family dinner for his mother and the rest of the royals at the restored Kew Palace in Richmond, Surrey.
Princes William and Harry and the Duchess of Cornwall will be among the HRHs there for the private get-together.
Charles will also be delivering his own televised tribute to the monarch, which will be broadcast to the nation.
The Queen, who will wake up on her big day at Windsor, will go on a walkabout with the Duke of Edinburgh to greet well-wishers outside the castle in the morning.
On Saturday, she will be joined by family and friends in the evening at Windsor for a party as the celebrations continue, but this gathering is also strictly private.
On Sunday April 23, the Queen, the rest of the royals, their friends and staff from the Royal Household will fill St George's Chapel in Windsor for a special service of thanksgiving.
The Queen, who is robust health for 80, will undertake various other 80-themed engagements throughout the week.
She will host a reception and lunch tomorrow at Buckingham Palace for 100 people turning 80 on the same day as her.