The body that is charged with making London's 2012 Olympic promises a reality starts work this week.
Tunnelling to put power cables underground has begun
The Olympic Delivery Authority (ODA) is responsible for making sure pledges like the £250m Olympic stadium in Stratford, east London, are delivered.
But little can be built until the site's 50 electric pylons are removed.
Four tunnelling machines have begun work in Stratford to route the power cables underground, which it is thought will take until 2008.
The ODA has six years to change Stratford into a 500-acre site fit to host the Olympics and Paralympics.
Olympics Minister Tessa Jowell said: "This is the start of something big.
"But this is about much more than 29 days of sport in the summer of 2012.
"This huge and impressive power lines project shows our determination to leave a lasting legacy for generations to come, improving lives and changing the face of London for ever."
There have been doubts about whether it can all be delivered on time, particularly in light of the problems that have dogged the £757m Wembley Stadium.
'No dramatic changes'
Asked how he could ensure the 2012 preparations went more smoothly, ODA boss David Higgins said the key thing was the planning.
"The first two or three years are the critical years to get things right," he said.
"If you don't make the right decisions then, then you have got problems."
He hopes to follow successful British projects, like the T5 project at Heathrow and the new Arsenal stadium.
The ODA will look again at the plans for the Games, investigating things like ground conditions, but also making sure the legacy is long-lasting regeneration in east London.
But Mr Higgins denied the promises made in London's Olympic bid would be watered down.
"There are no dramatic changes [being] considered," he said.
Some preparatory work for 2012 has already begun.
Earlier this week a huge boring machine started tunnelling beneath the Thames to extend the Docklands Light Railway in time for Olympic shooting events at the Royal Artillery Barracks in Woolwich.
Mr Higgins told the BBC: "We are going to be completed on time and I know the people of London and the UK are going to be very proud of what we have done."