The Olympic Flame will be lit on Thursday at a ceremony which signals to the world that the countdown to the London 2012 Games has begun.
The ceremony will take place in Olympia, Greece, where the ancient Olympic Games took place.
The flame itself is seen as representing positive values and is lit using the sun's rays to ensure that its purity is guaranteed.
Ritual states that this is the only way the Olympic Flame can be lit.
A team of the world's top Olympic and sports executives, including International Olympic Committee president Jacques Rogge, Hellenic Olympic Committee president Spyros Capralos and London 2012 chairman Lord Coe, will gather at the Ancient Olympia Stadium for the lighting of the sacred flame.
In front of the ancient ruins of the Temple of Hera, an actress playing the role of a high priestess will light the flame by the rays of the sun in a parabolic mirror.
The flame is then placed in an urn and taken to the ancient stadium where Spyros Gianniotis, 32, the world champion 10km swimmer, will be waiting to begin the first leg of the torch relay across Greece.
The Greek swimmer was born in February 1980 in Liverpool, to a Greek father and a British mother.
He will pass it on to 19-year-old Alex Loukos, who was one of the 30 East End schoolchildren who travelled to Singapore in 2005 as part of the closing presentations for London's bid.
Mr Loukos, a keen boxer, has been training for his role as the second torchbearer by running around the streets near his East Ham home.
The flame will visit Piraeus, Crete, Xanthi, Thessalonica and Larissa, among other places, in a relay around the Greek mainland and islands.
The torchbearers are transporting it from Ancient Olympia to the Panathenaic Stadium in Athens, where the first modern Olympics were held in 1896, for the handover to London on May 17.
The last torchbearers in Greece will be Li Ning, the Chinese gymnast , who lit the cauldron at the opening ceremony for the 2008 Beijing Games, and Greek weightlifter Pyrros Dimas.
Greece's economic and political troubles were not ignored by Mr Capralos, who stressed that "in spite of difficult times, Greece will be represented in the top sporting event with a particularly strong team."
The team numbers are set to rise from 75 as more teams and athletes qualify for the Olympics.
Capralos added: "The Hellenic Olympic Committee has pledged from the beginning to send to the Olympics all the qualified athletes and I am sure that they will fight in order to honour our country and Greek sports.
"Greece participates regularly in all the Olympics since 1896 and onwards and I believe that in the British capital we will prove that we honour and respect our ancestors' legacy that conceived and gave birth to the Olympic Games.
"At the same time we will send a message to every direction that our country is a proud country that does not give up easily.
"We face the same challenge on May 10 in Ancient Olympia, with the lighting ceremony for the London 2012 Olympic Games and a week later on May 17 with the handover ceremony of the sacred light to the British delegation, at the Panathenaic Stadium.
"The two ceremonies are a great opportunity for the Greeks wishing to give a dynamic presence, reminding the world that it all started here.
"Tourists visiting Greece are also invited to attend the ceremonies and travel back in time and in the history of Olympism and sport."
Following on from the May 17 ceremony, the flame is then flown to the UK, landing at RNAS Culdrose, near Helston, Cornwall, on May 18 for a 70-day relay around Britain.
Starting at Land's End, this will see 8,000 torchbearers carrying it from May 19 to the lighting of the cauldron at the opening ceremony at the Olympic Stadium in Stratford, east London.
The London 2012 Olympics begin on July 27.