The greatest team effort at these Olympics might be the one most people take for granted. The French capital is under more scrutiny than any athlete.

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Paris has the greatest challenge at its own games. The city has to host all these events impeccably, house the competitors, keep everyone safe, and deal with an inevitable array of unforeseen problems, while also keeping the capital moving and working.

And all this at a time when there is a war raging across the continent, and another conflict blazing in the Middle East, when fears of a terror attack simmer just as millions of people prepare to pay a visit to Paris.

What’s more, it all starts with an unprecedented, and wildly complicated, opening ceremony tonight. Instead of it being held in a stadium, the ceremony will be held along the River Seine, as it winds through Paris.

It will probably look great, but the ripples from this one-off ceremony spread far. For one thing, Paris will grind to a halt as roads are shut, bridges closed and around half a million people take to the streets to try to get a look at the ceremony.

Already the head of the city’s police, Laurent Nunez, has appealed for Parisians to park up their cars by 10am, and to stay at home from 3pm unless they have the pass required to watch the ceremony on the Seine.

On the river, specialist anti-terror police will be positioned on the riverbanks and will also be in boats along the course of the river.

There will be snipers on rooftops. The BRI, considered the special forces unit of the French police, will be deployed, along with helicopter patrols and specialist units to prevent drones from being flown. The centre of Paris will become a no-fly zone.

It is a massive policing challenge, and that’s just the first day.

A total of 45,000 police officers will be used during the games, along with 18,000 military personnel and around 20,000 people from private security firms.

On top of that, there will be nearly 2,000 officers in Paris drawn from 44 foreign police forces. Of those, 250 officers have come from the UK, having already offered advice from their experience of hosting the games in 2012.

Fears of terror attack

The greatest fear is, naturally, of a terrorist attack, on either the athletes or the spectators.

That’s why such a huge amount of effort has been put into controlling movements around the city. Millions will come to Paris to watch the sport and, in return, the police will be watching them.

Highest profile of all will be two groups. Firstly, the heads of state who come here, greeted today at a reception hosted by French President Emmanuel Macron at the Elysee Palace.

And second will be the athletes from Israel. Already they have been promised a higher level of protection than any other nation, with armed police following their football team to both matches and to training.

So far, the protests against them have been relatively low-key here – the anthem jeered at their first match – but at least one French MP has said the Israeli athletes were not welcome and it would be a surprise if we didn’t see more protests in the coming weeks.

That’s not the only potential disruption.

Concerns Russia will cause trouble

The French believe Russia has already spread disinformation about Paris’s preparations for the games, spreading stories Paris wasn’t ready and the event would be ruined by overbearing security.

Now there are fears Russia will attempt to cause trouble and disrupt the games, either through further disinformation or through cyber attacks on the infrastructure of the event.

Earlier this week, a 40-year-old Russian man was arrested on suspicion of planning to destabilise the Olympics.

Police raided his house and said they found evidence he was planning to “organise events likely to cause destabilisation” during the games. He is being held in detention and could, said authorities, face up to 30 years in prison – a hint at the gravity of the accusations against him.

Threat of industrial action

Then there are the other challenges – the demands on public transport, carrying millions of tourists around the event, will be mitigated by the number of workers who are now on holiday.

The threat of industrial action will hang over the whole games, with strikes threatened by workers ranging from dancers at the opening ceremony to Uber drivers, who claim they’re being treated as second-class workers.

And in the background, France remains a country without a functioning government, after an election that failed to produce a clear result.

Coalition talks have so far failed to come up with an acceptable candidate for prime minister and so the sitting leader, Gabriel Attal, will sit in the VIP section, even though he knows he’s almost certainly about to be jettisoned from his job.

The politicians have agreed an “Olympics truce” that may, or may not, last.

France’s most fervent ambition, though, is that the security stays in the background – a hope that this event is remembered for the sport, for the organisation and for the smiles of its volunteers.