All nine cities hoping to stage the 2012 Olympics have presented their plans to the International Olympic Committee (IOC).
The Stade de France forms an important part of the Paris bid
Each of the bidders had to submit their answers to a detailed IOC questionnaire by the 15 January deadline.
And the main contenders - London, Paris and Moscow began unveiling their bids at 0900 GMT on Friday.
"We are delighted to see that all nine cities have returned their dossiers on time," said IOC chief Jacques Rogge.
The questionnaire covers overall concept, finance, political support, security, accommodation, and infrastructure.
"There is still a long way to go until the election of the host city in July 2005. We wish good luck to all nine cities and look forward to a fair competition," added Rogge.
The race for 2012 could be one of the most keenly contested in Olympic history.
London has been installed as an early favourite along with Paris.
And London began revealing details of its plans at a ceremony at the city's Royal Opera House on Friday, while the French bid was launched with a glitzy ceremony at the Eiffel Tower.
Both cities have staged the Games twice, Paris in 1900 and 1924 and London in 1908 and 1948.
Madrid and New York are also considered to be strong candidates for 2012, with Moscow, Istanbul, Leipzig and Havana seen as outsiders.
The odds on Rio de Janeiro bringing the Games to South America for the first time have been cut in the past few days.
Rio has promised a compact Olympics, with an 80,000-capacity stadium planned for a site currently occupied by the Nelson Piquet racetrack.
"This project is magnificent, excellent, unique and historic because for the first time all the installations will be within the urban perimeter," said Brazilian Olympic Committee president Carlos Arthur Nuzman.
Moscow last hosted the games in 1980
"I can guarantee you that this project will excite the whole world."
An IOC panel will now study the bid questionnaires to determine whether the cities meet the criteria for hosting the Games.
The IOC executive board will decide in May whether to accept all nine as official bid cities or trim the field to about six.
The full IOC will select the host city in July 2005 in Singapore.
Paris has already gained a head of steam after hosting the 2003 World Athletics Championships last August and France's successful hosting of the football World Cup Finals in 1998.
London had been due to host the 2005 World Athletics, but plans to build a new stadium at Picketts Lock in the north-east of the city were scrapped amid much controversy.