LONDON (CNN) -- The 2012 Summer Olympics officially began with a flourish on Friday night with stirring odes to Britain's past and present, as tens of thousands packed Olympic Stadium to take in the lively, diverse and fast-paced show.
Organizers have said they expected a billion people worldwide to watch the opening ceremony -- which was created by Danny Boyle, best known for directing the Oscar-winning film "Slumdog Millionaire" -- on television. Tens of thousands more congregated in "fan zones" around the British capital to watch the festivities on big screens, their enthusiasm hardly diminished by overcast sky and sporadic showers as London welcomed the world as an Olympics host for the third time.
The event opened with a scene dubbed "Green and Pleasant," after a line from poet William Blake's "Jerusalem," that featured an idyllic view of a British countryside. Rolling hills, fields and rivers -- complete with picnicking families, sports being played on a village green and farmyard animals -- made up the elaborate set.
Hundreds of volunteers dressed in period costumes walked, danced and otherwise performed as music played. The set soon transformed into one featuring factories, recalling the Industrial Revolution, including large smokestacks emerging from below.
After a short film featuring Daniel Craig, the latest actor to play cinematic British spy James Bond, and none other than Queen Elizabeth II herself, the next performance paid tribute to Britain's National Health Service and children's literature. J.K. Rowling, author of the best-selling Harry Potter books, kicked off the scene -- which featured, among others, the evil Voldemort from her series and magical nanny Mary Poppins.
Next came a performance of the iconic song from "Chariots of Fire," a tale about two British Olympians from 1924 that was lightened up by slapstick comedian Mr. Bean. Then came a showcase for pop songs from the Beatles to the Rolling Stones to Frankie Goes to Hollywood to David Bowie, which was followed by a short live performance by rapper Dizzee Rascal.
There was also a special shout-out to Tim Berners-Lee, who is credited with inventing the World Wide Web. His words, "This is for everyone" at one point lit up a part of the stands for all to see.
Just over one hour in, the Olympic athletes finally made their way into the stadium led, per tradition, by the Greek delegation.
Some athletes competed in advance of Friday night's formal kick-off, including members of multiple men's and women's football squads. Earlier in the day, for instance, all 128 competing archers took part in a preliminary round at Lord's Cricket Ground in London to determine seedings for team and individual competitions.
Three South Korean archers took the top three seeds in the men's individual round, with the winner, Im Dong-hyun -- who is legally classified as blind -- setting a world record in the process, according to the official website for the Games.
Hours earlier, the day got off to a resounding start as bells around the country pealed for three minutes, including more than 40 chimes from London's famous Big Ben clock tower.
The Olympic torch, which has traveled around the United Kingdom over the past 70 days, then set off on the final leg of its journey toward Olympic Stadium, aboard the royal barge Gloriana.
Rowers propelled the vessel, which played a central role in Queen Elizabeth II's diamond jubilee celebrations, down the River Thames from Hampton Court to Tower Bridge.
Former Olympian rower Matthew Pinsent, tasked with carrying the flame on to the barge, said it was "a huge day for London."
Crowds lined the river's banks to cheer the torch along, adding to the more than 13 million who've turned out to watch it pass in the course of its 8,000-mile journey, according to the government.
International Olympic Committee chief Jacques Rogge declared the capital all set to host the world's greatest sporting event.
The IOC has "reviewed all the operational items, and I can say with pleasure that London is ready and we are eagerly waiting for the opening ceremony," he told reporters.
Just over 7,000 of the 10,500 athletes taking part in the Games have now arrived in the United Kingdom, the British government said.
U.S. first lady Michelle Obama met with members of Team USA at a breakfast Friday morning at the U.S. Olympic Training Facility, hours before she will lead the delegation as the athletes parade at the opening ceremony.
Katie Lawrence, a resident of the U.S. state of Georgia who holds dual U.S.-British citizenship, told CNN that she was hugely excited to be in London to watch the sporting extravaganza.
"I love the Olympic Games, I always have, always will. I'm always torn as to which team to root for, but I have no shame in rooting for both USA and GB," said Lawrence, who saw the 1996 Games in Atlanta as a child. "I cannot wait to be immersed in all of the excitement and bustle that the Games bring."
CNN iReporter Kevin Dunscombe, a Londoner,