A giant set of Olympic rings was revealed at St Pancras International station in central London.
The set of rings was unveiled by London Mayor Boris Johnson and London 2012 Chair Sebastian Coe.
The 20m-wide aluminium structure is suspended in the station's vast main space.
It is the first of several sets of rings which will appear on key landmarks around the city in the run up to next July's Games. The Games will begin On July 27 with the women's hockey tournament scheduled to being on July 29 and the men's tournament set for a July 30th start.
The rings, which were built in Hitchin, Hertfordshire, were secretly assembled and installed at St Pancras over seven nights.
Several sets of rings will appear on landmarks around London in the run up to the 2012 Games. Earlier on Thursday, people passing through the station could see a large structure shrouded in a cloth, hanging in front of Paul Day's sculpture of a kissing couple.
The station, a Eurostar terminus since 2007, forms a key part of London 2012 transport plans and 'Javelin' trains will take visitors from there to the Olympic Park.
The logo of five interlinking Olympic rings was designed by the founder of the modern Olympics, Pierre de Coubertin, and has been a symbol of the Games since 1914.
Coloured blue, yellow, black, green and red, the rings represent five continents and are linked to show unity between the world's athletes in the spirit of the Olympic movement.
It is traditional for Olympic rings to appear around the host city ahead of Games time.
In 2000, Sydney Harbour Bridge was adorned with a set, as was the Great Wall of China ahead of the Beijing Games in 2008.
Lord Coe said: 'The Olympic Rings are an iconic symbol, inspiring athletes and uniting people around the world. To athletes they represent the culmination of thousands of hours of training and reaching the highest level in sport.
'To Londoners and visitors alike, they will excite and inspire them about being in a host city and demonstrate that we are ready to welcome the world in 2012.'
London Mayor Boris Johnson said: 'Unveiling the first set of Olympic Rings at St Pancras International provides a fantastic glimpse into how the capital is gearing up for this unique event.
'The rings will be a powerful symbol for millions of visitors using the iconic station that the capital is poised and ready to welcome the world's greatest sporting stars and put on the best show on earth.'
Culture Secretary Jeremy Hunt said: 'The iconic Olympic Rings at St Pancras are a reminder to Londoners and visitors alike that the greatest sporting event in the world is now just round the corner.'
Source: BBC News & Inside the Rings Files
