Torch starts final leg before London Olympics open July 21, 2012 -- Updated 1115 GMT (1915 HKT) The Olympic torch will be carried all over London in the next week The 2012 Games open in the city Friday The torch relay has gone to more than 1,000 communities around Britain London (CNN) -- The Olympic torch relay began its first full day in London on Saturday, marking the start of the final week-long countdown to the opening of the 2012 Games. The flame was handed to the day's first torchbearer in Greenwich, home to the Equestrian Arena for the Games. The torch was also carried up to the roof of the North Greenwich Arena, where gymnastics events and the basketball finals will be staged. Later in the day, it will reach the Tower Hamlets neighborhood, one of the poorest in London, which has benefited from millions of dollars of investment in infrastructure and regeneration projects as a result of the Games. The torch made a dramatic arrival at the Tower of London on Friday evening, when a Royal Marine commando, carrying the flame in a lantern descended a rope 180 feet from a Royal Navy Sea King helicopter into the grounds. London Mayor Boris Johnson was there to greet the torch at the Tower, which dates to the 11th century. The flame spent the night in the safekeeping of the Jewel House, home of the Crown Jewels. Over the next week, nearly 1,000 torchbearers will carry it along nearly 200 miles of streets around the capital before it takes a starring role at the opening ceremony at the Olympic Park next Friday. More than 10 million people 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 over the past two months, Olympic organizers said. Some 3,500 extra military personnel have been called up to meet the shortfall in recruitment by G4S. Another 1,200 have been placed on standby as a contingency, the government said this week.