Britain launched the one-year countdown to the start of the 2012 Summer Olympics in London Wednesday with a day of festivities in the British capital and other cities around the globe.

A huge countdown clock was unveiled in central London.  International Olympic Committee President Jacques Rogge issued a formal invitation to all 202 nations with teams to send their athletes to Britain.

World champion swimmer Tom Daley inaugurated the aquatics center with the first dive into the swimming pool.

In New York, nine-time Olympic gold medalist Olympic track and field star Carl Lewis unveiled a countdown clock at the United Nations.  Countdown clocks were also dedicated in New Delhi and Beijing.

Britons and Canadians in Washington ran a ceremonial Olympic torch relay six kilometers from the Canadian embassy to the British embassy.

In Pakistan, the British High Commission's tennis team competed in a mixed doubles match with top Pakistani players. The British Embassy in Romania threw a street party in Bucharest.

British diplomats In Uzbekistan staged a mini-Olympics for teenagers, and in Brazil they held a tea party at the official residence in Brazilia.