Here are the main events:
Saturday: Epsom Derby
The Queen is an avid horse racing fan and still rides at the age of 86. The Derby is Britain's richest horse race and one of its five Classics.
The Queen will view the paddock and the winners' circle before leaving.
Sunday: "Big Lunch" and Thames River Pageant
Britons nationwide will get out the bunting and hold street parties, sitting down to share lunch with their neighbours, reminiscent of the silver jubilee in 1977, when around 10 million people joined in the merriment.
The Thames pageant is the highlight of the weekend.
Up to 1 000 boats from Britain, the Commonwealth and beyond will sail downstream through London in one of the largest flotillas ever assembled on the river.
Queen Elizabeth and her husband Prince Philip will travel in a specially-built red and gold royal barge, with family members following behind.
It will take 90 minutes for the flotilla to pass a single point along the 11km route, as music barges blast out pieces from contemporary to classical.
Royal lunch by Heston Blumenthal
Monday: Palace picnic, Concert and Beacon Lighting
Some 12 000 guests drawn from a ballot will spread out on the Buckingham Palace lawns for a picnic especially created by Michelin-starred chef Heston Blumenthal.
It includes coronation chicken, chilled country garden soup, tea-smoked Scottish salmon, strawberry crumble crunch and a cheese board served with chutney, all washed down with champagne.
The picnic is followed by a concert in front of the palace, featuring Paul McCartney, Kylie Minogue, and Chinese piano virtuoso Lang Lang.
Finally, the queen will light the national beacon, the culmination of some 4 000 beacons being lit across Britain and the Commonwealth.
Tuesday: Thanksgiving service, procession and balcony appearance
The day begins with a national service of thanksgiving at Saint Paul's Cathedral. The royal family will attend and some 2 000 others have been invited.
Queen Elizabeth and Prince Philip will then attend a reception at the Mansion House, while other royals attend a reception at the Guildhall.
There then follows a lunch at the 11th century Westminster Hall, the oldest part of the Houses of Parliament, attended by around 700 people representing various trades, charities and schools.
Carriage procession
After lunch, a carriage procession will take the most senior royals in the line of succession back to Buckingham Palace.
The queen and her husband will be in the first carriage, followed by Prince Charles, the heir to the throne, and his wife Camilla, then Charles's sons Princes William and Harry, with William's wife Catherine.
Those royals will appear on the balcony of Buckingham Palace, accompanied by a Royal Air Force flypast and a celebratory cascade of rifle fire.