The Olympic flame has been handed over to London organisers at a ceremony in the marble stadium in Athens that hosted the first modern Games in 1896.
The flame was presented to Princess Anne on Thursday in a ceremony at Panathenaic Stadium by the president of the Hellenic Olympic Committee Spyros Capralos.
London Games chairman and Olympic champion Sebastian Coe paid tribute to Greece, and thanked the hosts for providing suitably damp "British weather" for the ceremony.
London mayor Boris Johnson and former England soccer captain David Beckham were among the spectators.
Transferred to a small lantern by golden torch from a cauldron, it was being guarded overnight in the British embassy in Athens.
It was then being flown on a British Airways Airbus to a naval air base in south-west England on Friday.
A 70-day torch relay travelling 12,800 kilometres around Britain and Ireland begins at Land's End the following morning.
The relay will culminate with the lighting of the Olympic cauldron in the new stadium in east London.
The London Olympics start on 27 July.