Clarence House, the Queen Mother's home for almost 50 years and now the official residence of Prince Charles, is to open its doors to the public.
Work by British artist Graham Sutherland is on display
Royal fans can tour the 19th Century property and see the Queen Mother's collection of art and furniture, much of which remains in its original place.
It is the fourth summer of tours at the London house, designed by John Nash.
During World War II, it was damaged by bombing and used as a headquarters for the Red Cross and St John Ambulance.
Clarence House was built at a cost of £22,232 in the 1820s for the Duke of Clarence, who later lived there as King William IV.
The Queen, then Princess Elizabeth, and the Duke of Edinburgh spent their early married life at Clarence House with Prince Charles living there as a small boy.
From 1953 to 2002, the Queen Mother made it her home and carried out official duties there.
Foreign Heads of State would call in for afternoon tea on the first day of a State visit.
Now, it is the official London residence of the Prince of Wales, the Duchess of Cornwall and Princes William and Harry, and provides office accommodation for Prince Charles's household.
Works of art include pieces by 20th Century British artists John Piper, Graham Sutherland, WS Sickert and Augustus John.
Examples of Fabergé and English porcelain and silver, many relating to the Bowes-Lyon family, will also be on display.
Guided tours run from Tuesday until 8 October, except between 10 and 17 September.
The first of the annual summer tours was conducted in 2003 following a multi-million pound renovation.