A team from the International Olympic Committee has begun a three-day inspection of venues and preparations for the 2012 Games in London.
IOC inspectors will review venues, the ticket pricing scheme and the change of the marathon route from east London to the Mall in central London.
Inspectors would want an update on the "unhappiness in the East End", a member of the IOC executive board said.
Tower Hamlets council is seeking a judicial review of the change of route.
In September, London 2012 organisers announced that it will move the original marathon route through Tower Hamlets and the East End to central London.
The new route will cover Buckingham Palace, Birdcage Walk, St Paul's Cathedral and the Houses of Parliament.
The change angered east London councils but London 2012 said the decision was made for operational reasons and it was "fair and legal".
During the twice-a-year inspection, the IOC team will visit the Olympic Park site in Stratford and also look at the security, marketing and plans for test events due to begin in 2011.
John Armitt, chairman of the Olympic Delivery Authority, said: "This year is the toughest in terms of construction and we are at our busiest.
"We will enter 2011 with the confidence that more than three quarters of the construction project is complete and that all milestones to date have been achieved."
Sir Craig Reedie, who sits on the IOC's executive board, said: "In general they [inspectors] are very happy with London's preparations - now they will be wanting the organising committee to move on as quickly as possible with anything outstanding.
"They will want satisfaction that the changes to the marathon route are in place, and to know what is happening in relation to councils' unhappiness in the East End."
London 2012 chairman Lord Coe said: "Over the next year, we look forward to seeing the changing London skyline as the Park vision becomes a reality."
Olympics minister Hugh Robertson said: "Good progress has been made on the Olympic Park this year with the main stadia looking fantastic as we approach completion."