A choreographed ceremony was performed before the lighting of the specially crafted traingular torch. The triangular shape was designed to highlight that London is hosting the Olympics for the third time — they also hosted in 1908 and 1948.
Spyros Gianniotis, a Greek swimmer and Olympic silver medalist, was the first of 490 torchbearers to carry the flame on Thursday. The 32-year-old Liverpool-born Gianniotis will carry the flame across 1,800 miles of Greek soil before the flame is handed to London organizers on May 17 in Athens.
The relay will end at the Olympic Stadium during the opening ceremony on July 27 with the lighting of the cauldron. This year's Olympic games will run through August 12.
Click here to see photos of the Olympic Torch lighting ceremony >>