By Jonathan Head
BBC News, Bangkok
Anyone travelling to Bangkok from the end of September will find themselves flying not into the dilapidated old airport at Don Muang, but into a brand new, state-of-the art airport situated 25km east of the capital.
The huge terminal is due to open at the end of September
Called Suvarnabhumi (Golden Land), the project was held back by frequent changes of government in Thailand, until the election of Thaksin Shinawatra as prime minister five years ago, who made it a personal priority to get the airport built.
Even now Suvarnabhumi is mired in controversy over allegations of corruption during its construction and complaints from the travel industry that Mr Thaksin is forcing it to open before it has been fully tested.
From a distance it shimmers in the heat, a series of huge steel-and-glass hoops and sweeping triangles of fabric glinting with the sun.
Up close, the sheer size of the main airport terminal - the world's biggest single terminal building - takes your breath away.
Designed by the renowned architect Helmut Jahn, with concessions to indigenous Thai motifs that are hard to spot in the uncompromisingly modern design, this is building on a monumental scale, building that is meant to impress.
But will it work? Will it be as good to use as it is to look at?
IATA, the International Air Transport Association, which represents the world's airlines, and therefore Suvarnabhumi's main customers, is not convinced it will be, at least in the first few weeks. Nor is much of Thailand's travel industry.
"We want Suvarnabhumi to be a success," says Albert Tjoeng, from IATA. "But we want it to open only when it is operationally ready - there needs to be more meaningful consultation between the airport and the airlines which will use it."
Complaints by airlines about the cost of using the new airport have forced AOT, the airport authority, to bring down the charges.
But the airlines are far more worried that the airport will not be fully tested by the time it opens on 28 September and that there will be problems handling passengers, baggage and security.
Mr Thaksin has spearheaded the building of the airport
AOT has brushed these concerns aside, bizarrely even accusing the IATA spokesman of trying to favour rival airports in the region. But there is no getting away from the fact that this $4bn project has become embroiled in politics and prestige.
Tourism accounts for 14% of Thailand's GDP, and the new airport will play a vital role in keeping the numbers of visitors growing.
Having missed three other deadlines he set for it to open, Prime Minister Thaksin insisted it must open by 28 September - his critics argue that this is in order to benefit him before a difficult election scheduled for November.
"He wants to open the airport before the election to project an image that he's in charge, that Thailand is going somewhere under his government," says Thitinan Pongsudhirak at Chulalongkorn University.
After the chaotic openings of some other airports in Asia in the past, IATA drew up a check-list for airport developers to follow, which it says enabled Incheon in South Korea and Chubu in Nagoya, Japan, to open smoothly.
The airport is the world's largest single terminal building
The association says it cannot understand why AOT has not followed their example.
But AOT insists there will be no serious problems.
I was taken on a tour by the authority during the final weeks of preparation. Thousands of staff from the old airport, the national airline and volunteers from the army were practising check-ins, security screening, passport control and baggage collection.
The spectacular building gave a tremendous feeling of light and airiness, although it might seem a little cold or intimidating for those used to the quieter and more intimate atmosphere at Bangkok's main rival airport in Singapore.
AOT claims Suvarnabhumi sets a whole series of world records - the largest single terminal building, at 563,000 sq m; the tallest control tower; and arguably the longest-delayed opening, 45 years since the project was first mooted.
A series of large-scale works of art have been commissioned to decorate the new building, ranging from impressive murals in the baggage-collection hall to some slightly garish reproductions of Thai mythical figures.
After checking in, passengers will be presented with kilometre-long corridors of duty-free shops, although critics say not enough space has been given to retailers, forcing King Power, the company controversially awarded a monopoly over duty-free outlets, to charge much higher prices.
But facilities should be much better than at the old airport, including a spa and a bowling alley.
Transport to the new airport is another matter.
There are still concerns about transport links to the terminal
A new rail link is not expected to open for at least two years; there is good access from expressways, but Suvarnabhumi is further from Bangkok than the old airport, and there is still some confusion over whether taxis will be allowed to pick passengers up directly from the terminal.
So by 0300 on 28 September, Bangkok's old airport at Don Muang, which has done sterling service accommodating tens of millions of travellers, will have seen off its last commercial flight.
Few will miss its shabby departure and arrival halls.
But there are likely to be plenty of anxious moments for passengers and airline officials during the new airport's first weeks, as they find out whether Suvarnabhumi will live up to its ambition to be one of the world's leading transport hubs.