London Mayor Boris Johnson gave the order to lower the rings with a few words barked into a walkie-talkie from a barge circling below.
The fusing of a London icon - the gateway to the city - with the rings signals London’s readiness to go one month before the Olympic games, which start July 27 and end on August 12.
"We are as ready as any city has ever been at this stage in the Olympic process,'' Johnson said. "I think probably better.''
The massive rings - 25 metres (82 feet) wide and 11.5 metres (37 feet) tall - are part of efforts to bedeck the city in Olympic banners and bold colours.
Things are looking bright
Meanwhile, all over London, the theme colours of the games are being raised on light posts, city buildings and in shopping areas.
London's look is predominantly pink, aqua blue, yellow, purple and green - not quite neon but usually shown in shards at the edges of Olympic banners.
There's even a ``Look Book'' for ideas. Local neighbourhoods can purchase materials to festoon their buildings in games-approved decor.
What a beach!
With most of the Olympic venues finished, one of the few big projects still under way is the beach volleyball venue on the Mall in central London. The construction had to wait because of celebrations marking Queen Elizabeth II's 86th birthday and her Diamond Jubilee celebrations of 60 years on the throne.
It's a big project - not just a few piles of sand and some bleachers. A 15,000-seat arena is being built, complete with lighting rigs, facilities for athletes, media and staff, six training courts and security screening areas.
And yes, there is sand. Lots and lots of it - about 4,115 tons.Dance to the music
The British rock trio Muse has recorded the official song for the 2012 London Games.
The song, ``Survival,'' was being broadcast for the first time on BBC radio Wednesday. It will be played during the July 27-August 12 games as athletes enter the venues and before medal ceremonies.
Muse frontman Matt Bellamy says the song was written with the Olympics in mind and ``expresses a sense of conviction and determination to win.''
Last month the trio carried the Olympic torch through their hometown of Teignmouth in southwest England as part of the flame's 8,000-mile (12,900-kilometre) journey to the games
Listen to Survival: http://www.youtube.com/watch?v=WXxTHFTSUlE