When police officers are high-fiving exuberant sports fans you know something is afoot. This isn't crowd control as we know it - but then again London 2012 has been no normal Olympics.
I was lucky enough to be at the Olympic Stadium on Sunday to see the mercurial Usain Bolt glide over the finishing line in the 100m final. My brother had applied for tickets along with two million other people and got them.
It was a privilege to see the fastest man in the world in action. But perhaps what will live in the memory most for me is the collective Olympic fever that has taken hold in London.
The police high-fiving was just one heartwarming example of this. Another one was taking part in a Mexican wave as we, along with a thousand of others, waited for our Javelin train to St Pancras station from the Olympic Park.
Undoubtedly, Team GB's success in the Games has contributed to the feelgood factor. There is much flag-waving but it is in a way that is alien to football or other sports.
Great respect was shown to other countries - and last Sunday some of the biggest roars of the night were for the Kazakh triple jumper Olga Rypakova and an entertaining high jumper.
The traditional British sense of humour was also on show as chants of 'Rooney, Rooney' went round the stadium for GB's Martyn Rooney.
London has taken the Games in its stride and confounded all the doom-mongers. Everywhere one can hear the song London Calling, a symbol of the capital's musical heritage and the renaissance of a 'Cool Britannia' spirit. It is a stark contrast to a year ago when The Clash's London's Burning seemed to encapsulate the zeitgeist better.
In a way, one could see London 2012 as symbolic of the transformative effect of sport. The athletes who have competed have been a wonderful example of dedication that have inspired us at a time when inspiration is sometimes lacking in other fields.
Politicians may seem powerless in the face of the Great Recession but Boris can get a bounce from the Games - though really they are a legacy of Blair's Britain, perhaps the former PM's most positive legacy to stand alongside his work on the Northern Ireland peace process, the minimum wage and devolution.
The ripple effect of the Games can be felt at home - my wife, who normally would rather watch a movie marathon than a sporting marathon, has been glued to the TV as the human drama has unfolded. Of course, the begrudgers will claim that the Olympic spirit will evaporate as soon as the Games are over.
They'll also complain about what a waste of money it all was. But those people fail to see how human experience is not just about pounds, shillings and pence. It's also about hope and glory and aspirations.
The tangible benefits for London will be an undoubted boost in the city's world profile.
Less measurable will be the memories left behind and the reaffirmation of the good in sport and human nature.
The Olympic flame may soon move to a new destination but London 2012 will always leave a glow in my heart. Even seeing a lightning Bolt comes second to that.