The site is far from finished, the project has been plagued by corruption scandals and there are fears of disruption by protestors opposed to it taking place at all.
Yet somehow Expo Milan 2015, the first world fair since Shanghai five years ago, will open its doors on Friday -- and Italy's Prime Minister Matteo Renzi is insisting everything is going to be just fine.
As frantic round-the clock preparations continued right up to the last minute, all the signs were that the specially-constructed 110-hectare site on the outskirts of Italy's economic capital would be some way from being completed in time for Friday's grand opening.
The 2.5-billion-euro ($2.8 billion) project has been beset by corruption scandals, which have contributed to the delays, and by fears the Expo itself could be the target of violent demonstrations by opponents who say the massively indebted Italian state should not be ploughing money into an ephemeral event at a time of economic hardship for many Italians.
Such objections were brushed aside by the youthful and bullish Renzi, who inherited the job of hosting the Expo from his predecessors but has embraced it as an opportunity for Italy to present a different face to the world: a confident, creative country that is facing up to its problems and acting to address them.
"We are ready for the Expo. Finally," Renzi said this week. "It could be better, it could have been held somewhere else and it could have been ready earlier: in these final hours I have heard many criticisms, which is fair.
"But it is here and it is going to be really great."
With its nutrition and gastronomy-based theme of "Feeding the planet, Energy for life," the six-month long Expo should play to Italy's strength as one of the global reference points for all things culinary, strengthening the made-in-Italy brand that is so important to its huge food production and tourist industries.
With 20 million visitors expected over the six months, organisers have predicted a 10-billion-euro boost to the economy. Half the benefits are projected to come from increased tourist spending and the balance in longer-term spin-offs in the form of increased inward investment.
Finance Minister Pier Carlo Padoan has billed the event as "a symbol of recovery and confidence."
- One million Chinese -
Hopes are high in particular that Italy's flourishing business and trade ties to China will be given a major filip with more than a million Chinese nationals expected to visit Milan -- more than the total that would usually come to Italy over the course of an entire year.
China's architecturally stunning pavilion, an ambitious but successful attempt to reflect the country's traditional rural and modern urban landscapes in one building, is expected to be one of the major draws for visitors from all corners of the planet.
More than 50 countries will host their own exhibitions in purpose-built national pavilions and more than 140 representing more than 90 percent of the world's population will have a presence of some form before an audience of up to 250,000 people per day.
Among them will be Nepal, whose pavilion will be the first to be visited by Renzi as an act of solidarity over this week's devastating earthquake.
Many of the Nepalese officials and artisans who were working on the pavilion have flown home but their places have been taken by Italian volunteers and it will be ready for the opening.
Milan last hosted a world fair in 1906 and the city is, like Italy, hoping to reap considerable benefits from its second shot at hosting an event that began with the 1851 Great Exhibition in London.
After over a century in which it has drawn its wealth from industrial manufacturing and related financing, Milan is seeking to reinvent itself for a world in which culture, design and leisure industries play an ever more significant role in generating prosperity.
That partly explains the city authorities' profound anxiety over the possibility of anything preventing the Expo from running smoothly and peacefully.
Fears the event could be targeted by terrorists mean security will be tight, with visitors protected by airport-style security with a perimeter fence, scanners at entry points and some 2,000 cameras.
And there will be a huge police presence on Friday, when up to 30,000 supporters of the "No Expo" movement are due to march.
Earlier this week, police carried out pre-emptive raids on radical groups suspected of planning to ensure the demonstration turns into a showdown with the security forces.
Officers seized fireworks, baseball bats, gas masks and material which could be used to make Molotov cocktails.
A German national was arrested for possession of explosive material and 26 other people, including 16 French nationals, were placed under investigation.
"No Expo" organisers accuse the police and media of whipping up public alarm because they are fearful that there will be more people protesting than visiting the Expo.
As well as objecting to the money spent, the opponents say the Expo is based on the exploitation of thousands of young people working for free and that its original conception as an environmental event has been skewed by the involvement of corporations such as McDonalds and Coca Cola.