The head of the UN's Environment Programme has backed the green measures adopted by the 2012 Olympic Games.
Achim Steiner said the organisers had shown how sustainability could be delivered for a "mass-scale event".
Mr Steiner's visit to the London venue coincided with the publication of a pre-event environmental report by the Games' organisers.
The UK capital won the right to host the Games in 2005, after beating other candidate cities including New York.
"Efforts such as greening of the supply chain, regeneration of an inner-city and bring energy efficiency to local homes, can build the confidence to wider society that sustainability is not theory but infinitely do-able," Mr Steiner said.
"Once the Games are over, I look forward to analysing the achievements and lessons learned."
David Stubbs, head of sustainability for the 2012 Games, said: "The complexities of trying to address sustainability in areas that have never been considered before was a constant challenge."
Among the highlights, which the organisers believed helped them secure the 2012 Games, are:
Seb Coe, chairman of the Games, said that the 2012 Olympics was already setting records, even before the first competitor had arrived.
"As we wrap up construction, preparation and planning and move into staging the Games, London 2012 is setting new standards," he said in the foreword to the report.
"We're establishing world records right now that will raise sustainability standards and benefit entire industries from construction to event management."
A key factor of the London bid was the concept of "legacy".
Members of the bid team acknowledged that it was necessary to reduce the impact of the largest peace-time event, and that the International Olympic Committee (IOC) wanted to move away from so-called "white elephant" venues, which added little value to a host city after an Olympics/Paralymics was over.
Last April, in their first environmental report, organisers said they were on target to cut the carbon footprint by 100,000 tonnes of carbon emissions in the procurement of materials and venue construction.
Speaking at the time, organisers said they were on track to deliver the world's first "truly sustainable" Olympic Games.
The team said their environmental vision focused on four areas: low-carbon emissions, waste, biodiversity, and promoting environmental awareness.