Britain's Queen Elizabeth hosts pop royalty at an evening concert outside her London residence Buckingham Palace on Monday night (local time).
This is one part of four days of nationwide celebrations for the Diamond Jubilee marking her 60th year on the throne.
Ten thousand ticket-holders will watch the performances live on a circular stage and much larger crowds are expected in surrounding parks to hear Paul McCartney, Stevie Wonder, Elton John and Jessie J entertain the 86-year-old monarch.
Ska band Madness will join the festivities by singing 1980s hit Our House from the roof of the 775-room palace, and the BBC, due to air the concert live, promised "one of the most spectacular shows ever staged in the UK".
Take That frontman Gary Barlow was brought in to organise the event. He and musical impresario Andrew Lloyd Webber penned a song for the jubilee.
It appears on souvenir album 'Sing', featuring acts from across the Commonwealth of mostly former British colonies, which went straight to number one in the album charts on Sunday.
After the concert, a network of 4000 beacons will be lit across the United Kingdom and Commonwealth, leading into Tuesday, the final day of the extended holiday weekend.
HORSES, BOATS AND CARRIAGES
On Sunday, more than a million people braved the pouring rain to watch a spectacular flotilla of 1000 vessels accompany the Queen on her gilded royal barge along the River Thames.
Organisers said millions more Britons spilled on to streets bedecked in Union Jack bunting up and down the country for outdoor parties marking the queen's milestone anniversary, although numbers were kept down by inclement weather.
The monarch indulged her passion for horse racing with a visit to the Epsom Derby on Saturday.
The jubilee concludes on Tuesday with a thanksgiving service at St Paul's Cathedral, a carriage procession along the Mall avenue, a fly past and farewell wave from the royal family to crowds gathered in front of Buckingham Palace.
The events, years in the planning, have underlined broad support for the queen in Britain, where she is riding high in opinion polls and is seen as a symbol of service, stability and national unity.
The displays of pomp and pageantry also gave a lift to many at a time of economic austerity and spending cuts, and boosted confidence ahead of the summer Olympic Games.
"You wouldn't get that anywhere else in the world - only the British could put on an event like that," said Paul Slater, a 30-year-old financial consultant who travelled from the central English city of Birmingham to watch Sunday's armada.
"Bring on the Olympics."
Support for the royal family is not universal however, with views ranging from indifference - around two million Britons travelled abroad to benefit from the extra days off - to outright opposition.
"Her achievement is just staying alive, doing little and saying less," Graham Smith, head of campaign group Republic said.
Queen Elizabeth is only the second monarch to mark 60 years on the throne, after her great-great-grandmother Queen Victoria reached the milestone in 1897.
She is also on course to become the longest-serving British sovereign in 2015.
The Queen's reign began in 1952, when she was 25, and has spanned 12 prime ministers from Winston Churchill to the current incumbent David Cameron.