Once the torch reached its final destination inside the Olympic Stadium, it was used to ignite the cauldron during the opening ceremony on July 27. The flame traveled 2,875 kilometers (1,786 miles) through the United Kingdom over 70 days.
Five-time Olympic rowing gold medalist Steve Redgrave of Britain carries the torch during the opening ceremony and then hands it off to a group of young athletes.
Young athletes carry the Olympic torch toward the cauldron during the opening ceremony.
The Olympic flame is lit inside the stadium.
The athletes ignited an outer rim of torches, setting off a chain reaction, spreading fire to other pieces until the cauldron was engulfed.
The individual torches rise up to form and engulf the cauldron in fire.
A wide view of the cauldron lighting inside the Olympic Stadium.
As the pieces rise, the cauldron is formed.
The lit cauldron inside the Olympic Stadium.
The Queen's royal row barge Gloriana carries the Olympic flame along the River Thames past the Parliament on Friday, July 27, the final day of the torch relay in London.
Musician Tyler Rix lights the Olympic cauldron during the torch relay finale concert in London's Hyde Park on Thursday, July 26.
Torchbearers Jennifer Saunders and Joanna Lumley, known for their "Absolutely Fabulous" characters Edina and Patsy, carry the Olympic flame through Lambeth, Kensington and Chelsea on Thursday, July 26, in London.
Torchbearer Ifeyinwa Egesi holds the Olympic flame inside the Globe Theatre in London on Thursday.
Torchbearer Rhyania Blackett-codrington, right, passes on the Olympic flame to comedian David Walliams, left, before setting off from Islington Town Hall July 26.
The Olympic torch is carried Thursday on top of an open top bus down Oxford Street in London.
Indian Bollywood actor Amitabh Bachchan, center, carries the Olympic flame through the streets of London on Thursday, July 26, the day before the opening ceremony.
Wheelchair basketball player Adedoyin Adepitan of Great Britain carries the Olympic flame Thursday over Millennium Bridge in front of St. Paul's Cathedral in London.
Torchbearer Paris Walker holds the Olympic flame Thursday as it travels on a barge at Camden Lock in London.
Torchbearer Daniel Mccubbin holds the Olympic flame inside St. Pancras International Railway Station on Thursday, July 26.
Torchbearer Scott Moorhouse, a Paralympic javelin thrower, runs with the Olympic flame along Tottenham High Road in London on Wednesday, July 25.
Spectators watch as the flame makes its way up Tottenham High Road on Wednesday, July 25.
James Cracknell carries the Olympic flame on the torch relay leg through Kingston Upon Thames on Tuesday, July 24. The flame is traveling 2,875 kilometers (1,786 miles) through the United Kingdom over 70 days. Its journey ends Friday at the opening ceremony of the London 2012 Olympic Games.
Explorer Amelia Hempleman-Adams carries the Olympic torch as she stands on the roof of a pod on the London Eye in central London on Sunday, July 22.
A spectator sits atop a phone booth as people gather to watch the Olympic torch pass through Greenwich in London on Saturday, July 21.
Torchbearers "kiss" their torches to pass the Olympic flame during the London 2012 torch relay through the Borough of Tower Hamlets in London on Saturday, July 21.
British Royal Marine Martyn Williams abseils from a helicopter with the Olympic flame into the grounds of the Tower of London on day 63 of the 70-day relay, which has involved 8,000 torchbearers.
British sailor Sir Robin Knox-Johnston runs around the restored Cutty Sark ship with the London 2012 Olympic Torch in Greenwich, south London, on Saturday July 21.
David Boyle carries the flame on a boat rowed by the Maidstone Rowing Club during his leg through Maidstone, England, on July 20.
Christopher Bury carries the flame through Mote Park in Maidstone, England, on July 20.
British artist Tracey Emin holds the Olympic flame inside the Turner Contemporary Gallery in Margate alongside "The Kiss" sculpture by Rodin on Thursday, July 19.
Torchbearer Daisy Shepherd of East Sussex carries the Olympic flame through Hastings on the southern coast of England on Wednesday, July 18.
Torchbearer Kathy Gore of Uckfield runs with the Olympic flame at Seaford Head in front of the Seven Sisters cliffs in East Sussex on Tuesday, July 17.
Keith Leech of Hastings uses the Olympic flame to light the cauldron in Hastings on Tuesday, July 17.
Thomas Mules carries the Olympic flame on Pulpit Rock, Portland Bill, on Friday, July 13.
Relay fans watch Andrew Clutton from the top of a ship's mast as he carries the Olympic flame between Hamworthy and Poole on Friday, July 13.
Ryan Hope carries the torch Thursday, July 12, on the row boat Penny off the waters of Weymouth.
Schoolgirls outside Salisbury Cathedral on Thursday hold the torch carried by retired sprinter and four-time gold medal winner Michael Johnson.
Olympic gold medalist and former sprinter Michael Johnson carries the flame at Stonehenge onThursday.
Prince Philip, Queen Elizabeth II and Lord Sebastian Coe watch as Olympic torchbearer Gina Macgregor passes the flame to Phil Wells at Windsor Castle in Windsor, England, on July 10.
Competitive canoeist Zachary Franklin carries the flame at the Lee Valley White Water Centre in Waltham Cross, England, on July 7.
Lauren Reeder, a teaching assistant, is surrounded by local children while carrying the torch in King's Lynn, England, on July 4.
Retired police officer Glenn Chambers carries the flame through heavy rain in Lincoln, England, on June 28.
Torchbearer Eugene Perry carries the Olympic flame at Sutton Bank in the North Yorkshire Moors National Park in York, England, on June 20.
Joseph Forrester, 12, and children from Madras College run along West Sands in St. Andrews, Scotland, on June 13.
Andrea Strachan, a competitive swimmer, carries the Olympic flame along the shore in Lerwick, Scotland, on June 10.
Actor James McAvoy carries the torch down Buchanan Street in Glasgow, Scotland, on June 8.
Triathlete Peter Jack holds the Olympic flame while on the Giant's Causeway in Northern Ireland on June 4.
Comedian John Bishop carries the Olympic flame on top of the Jodrell Bank Observatory in Jodrell Bank, England, on May 31.
Television presenter, adventurer and writer Ben Fogle carries the Olympic flame in a hot air balloon on May 19, the first day of the relay.
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame lands in London
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
The Olympic flame's journey
STORY HIGHLIGHTS
- A Royal Marine commando will bring the flame from a helicopter into the Tower of London
- Torchbearers will carry the flame along 200 miles of London streets this week
- The Olympic Games open in the city on July 27
- The buildup to the Games has been overshadowed by a fiasco over security guards
Are you getting excited for the Olympics next week? Share your Olympic sights and sounds with CNN's iReport.
London (CNN) -- The Olympic torch is set to make a dramatic entry to London Friday, descending via a 180-foot line from a helicopter to the historic Tower of London.
The torch's arrival in the capital begins the final week before the Games open and the final stage in its long journey.
More than 10 million people have already lined the streets of more than 1,000 communities around Britain to see the torch, which has been carried by more than 7,000 torchbearers, Olympic organizers said.
Nearly 1,000 more will carry the torch along nearly 200 miles of London streets over the coming week, before it takes a starring role at the opening ceremony at the Olympic Park on July 27.
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Eighteen torchbearers will carry the flame on the final day of the relay, with seven of them traveling with it down the River Thames on the royal barge Gloriana, which played a central role in the Diamond Jubilee river pageant for Queen Elizabeth II.
The torch's arrival at the Tower of London on Friday evening promises to be eye-catching.
A Royal Marine commando, carrying the flame in a lantern, will abseil -- the technique known as "rappel" in the United States -- 180 feet from a Royal Navy Sea King helicopter into the grounds, where London Mayor Boris Johnson will be waiting to greet it.
The torch will be carried around the Tower, which dates back to the 11th century, before spending the night in the safekeeping of the Jewel House, home of the Crown Jewels.
The buildup to the Olympics has been overshadowed by a security fiasco caused by the failure of contractor G4S to supply enough guards for the Games.
2012 Olympic flame lit in ancient stadium
But Johnson told CNN's Becky Anderson that while London authorities are not complacent, he is confident in their ability to keep visitors safe.
"We do everything in our power to maximize security at the venues and that's working well now -- the army, the military as well as G4S are providing very safe conditions on the site, plus there is a huge amount of work that nobody has seen involving the intelligence service," the mayor said
"That's something about an event like this -- you listen out for what may or may not be happening on the Internet, you try as hard as you possibly can to monitor the potential suspects."
Johnson said it is impossible to guard against all "unknown unknowns" and that's why strong security is needed at venues.
"At no stage can you guarantee that someone won't do something moronic, stupid, violent and tragic, not just in London but the whole of the UK is a potential target in this period," he said.
Olympic cyclist comes full circle
London's Olympic torch lit in Greece
Olympic torch relay begins in Greece
But at the same time, he said, "the intelligence is as reassuring as it could be under the circumstances. The threat level as far as we are aware has slightly come down in the last 12 months, but you can never be certain."
Look at photos of the journey of the Olympic flame
Authorities said Thursday that an additional 1,200 British troops were being placed on standby for the Olympic Games.
The company's recruitment shortfall had already forced the government to call in 3,500 extra military personnel to help.
Culture Secretary Jeremy Hunt, the minister in charge of overseeing the Games, said that there was no need to deploy extra troops but that putting 1,200 on standby means they can be moved within 48 hours rather than seven days if required.
G4S has a £284 million ($444 million) government contract to provide 10,400 security staff for the Olympic Games, but only about 4,000 guards are trained and ready.
It expects to provide at least 7,000 by the time the Games start, chief executive Nick Buckles told lawmakers earlier this week.
Home Secretary Theresa May gave more details on how the fiasco unfolded in a letter sent to the head of Parliament's Home Affairs Committee on Thursday.
Although the Home Office did not become aware of the full extent of the shortfall until July 11, G4S had alerted the government to "scheduling problems" affecting staff numbers on June 28, she said.
Once it became clear how large the shortfall would be, the government put its contingency plans into operation, she wrote.
"G4S will still be making a substantial contribution to venue security," she wrote.
"All G4S personnel working on venue security duties will have had training for the role they are undertaking," May added.
The G4S recruits are supposed to perform tasks including venue perimeter security, such as manning X-ray machines, searching people, searching vehicles and operating closed-circuit television systems, the company said.