Sixty years after she ascended to the throne in an austere Britain still facing post-war rationing, the Queen marked the milestone on Monday with a new website that showed just how much the world has changed during her reign.
The 25-year-old princess was on tour in Kenya when she became queen on February 6, 1952, following the death of her father, King George VI. She immediately flew back to Britain where she was welcomed by then Prime Minister Winston Churchill.
The royal family has been through tumultuous times since then. Three of the queen's four children have divorced and every personal crisis has been dissected by world media.
The most extreme case was the 1997 death of Princess Diana, ex-wife of the queen's eldest son Prince Charles, a rare moment of mass unpopularity for the monarch who was criticised for not showing enough emotion amid a national outpouring of grief.
During her reign, the royal family has also repeatedly come under fire over its expensive lifestyle and the queen has had to give up some of her privileges, such as her beloved yacht Britannia, which was decommissioned in 1997.
But over time, the monarch's restrained behaviour and devotion to duty have endeared her to most Britons. She also benefited from the goodwill generated by the glamorous wedding of her grandson Prince William and Kate Middleton last year.
In typical low-key style, the 85-year-old queen spent Monday carrying out routine duties such as a school visit in the town of King's Lynn in eastern England, prompting one fan to tweet that it should be renamed Queen's Lynn for the occasion.
Four days of more lavish celebrations of her 60 years on the throne, known as the diamond jubilee, are scheduled for June when the weather will be warmer. These will include a 1,000-ship pageant on the River Thames and a concert at Buckingham Palace.
60 YEARS, 30 CORGIS
The queen promised on Monday to dedicate myself anew to your service.
I hope also that this Jubilee year will be a time to give thanks for the great advances that have been made since 1952 and to look forward to the future with clear head and warm heart, she wrote to her subjects in a message.
The royal household launched a festive new website, thediamondjubilee.org, allowing users to send the queen a message, listing 60 interesting or amusing facts about her, and featuring a photo timeline of world events during her reign.
The queen is now the second longest-serving monarch in British history after Queen Victoria, who reigned from 1837 to 1901.
During Elizabeth's reign there have been 12 British prime ministers, 12 U.S. presidents and six popes.
Among the 60 facts listed on the website were details about the queen's favourite dogs: she has owned 30 corgis during her reign, and has three at present, Monty, Willow and Holly.
The queen has answered approximately 3.5 million letters, sent about 45,000 Christmas cards and given out some 90,000 Christmas puddings to staff over the years.
The timeline includes world events ranging from the first ascent of Mount Everest in 1953 to the Arab Spring protests in 2011, as well as personal milestones such as the birth of Savannah, her first great-grandchild, in 2010.
It even includes a picture of legendary punk band the Sex Pistols signing a record deal in front of Buckingham Palace - although it stops short of mentioning their 1977 hit song God Save the Queen, which the BBC banned at the time over lyrics deemed too disrespectful towards the monarch.
(Additional reporting by Michael Holden; Editing by Alessandra Rizzo)