TRUMP TOWER is a cliff of glass and steel, 58 floors high, on the most expensive stretch of Fifth Avenue, New York. It is open to the public to show us the money: "Gucci, coming soon!" When Donald Trump sweeps in, flanked by two impeccably suited heavies, it causes a stir. "Look at all these people taking your picture," he tells his companion, with a winning charm that would sound rehearsed coming from anyone but the most famous businessman in America. Trump is his own best customer, a brilliant method actor, so immersed in his role that man and myth are inseparable.

The security men wave me into a different elevator. Trump will see me when he is good and ready, once I have had a moment to look at Central Park through the glass wall of his office, time to flick through the high-roller publications carrying his profile, the programme for his Miss Universe contest and Trump Magazine itself. The big story inside is the launch of Trump Vodka, an ostentatious gold bottle full of "success distilled".

Trump's image is everywhere, floor to ceiling, in frames too many to count. They cover every inch of wall space, in the waiting room, along the corridors, surrounding his secretary in her alcove. He is on the cover of Esquire, Vanity Fair and GQ, here grinning as he cuts the red ribbon on a new building, there picking up an award or shaking hands with a celebrity. His hair never changes. There is a box of books on the floor, waiting to be signed - Think Big And Kick Ass In Business And Life.

After about a quarter of an hour, I am summoned into his personal space. There are signed basketballs, American football helmets, a shelf littered with trophies and yet more photos of the man sitting behind the desk. His handshake is firm, his gaze direct: "Tell me about this newspaper. How big is it?"

Before I can even sit down, he hands me a sheaf of glossy paper and cardboard: a New York Times printout, a rich list and a portfolio of properties from "the biggest name in real estate by far!" The architecture column approving of Trump World Tower (not to be confused with Trump Tower, Trump Palace, Trump Plaza, the Trump Building or Trump Place) was written in 2002. The ranking sheet of New York's privately owned companies that shows him ahead of Bloomberg, Hearst Corp and Warner Music Group was drawn up in 2004.

"I'll give you a little information so it's easy for you," he says. "This is a recent review of one of my buildings, this shows that we're the number one private company in New York." He has several copies of each and I get the impression that he hands them to his guests as a matter of course.

For the first minute, Trump asks all the questions: "This is not about the guy with the land, I guess, is it? Is that a big story? Not particularly, right? You know he's not in our way; do people understand that?" And like that, we're off, into the Michael Forbes as Local Hero story that fairly or unfairly casts Trump as Burt Lancaster playing Felix Happer, the unscrupulous American businessman trying to buy a chunk of Scotland.

For the fictional fishing village of Ferness, read Menie Links. For oil, read golf. Trump plans to build a resort by the North Sea, but as he only trades in superlatives it will be "the greatest golf course in the world. We have more frontage on the ocean, better links, bigger dunes."

He says: "Somehow there's the misconception that I need that land - absolutely false. But what we would like Forbes to do is clean up his land. He should be ashamed of himself, it's a terrible representation of Scotland. My mother was from Scotland and she would not be terribly happy to see what he's doing with that land.

"It's in total disrepair. It's not taken care of. It's got rusting oil cans, tractors that haven't been used in years. It has nothing to do with our golf course, other than that it looks bad for the country of Scotland. If I had a choice between buying his land and him fixing it up, I would rather have him fix it up." He repeats this last sentence four times. Having failed to buy Michael Forbes, so far, he is trying his hardest to ignore him.

The two golf courses, the hotel and the holiday homes that Trump hopes to build are presented as a personal project, the closing of a circle that opened in the 1930s when his mother left the village of Tong, on the Isle of Lewis, and boarded a ship to New York. "Because of the relationship of this project to my mother, this is my most important job," Trump says. "From the standpoint of legacy I would rate this at the top.

"I make money doing a lot of different things. I don't need this project. If my mother wasn't born in Scotland, I wouldn't do it. It is an amazing story if you think about it. My mother came from Stornoway and here I am the biggest developer in New York, one of the biggest in the world. That tells you about the Scottish people."

Trump has the practised ease of a politician, forever ready with a soothing remark, generous with his blandishments. He talks airily of having "a great feeling for Scotland", praises Scots for their drive and namedrops Sean Connery, "the first official member of my club".

He calls Alex Salmond "a brilliant man", but won't reveal whether the first minister supports the development, perhaps mindful of the trouble that Salmond's predecessor Jack McConnell stepped into when he offered his enthusiastic backing last year.

TRUMP has never worn the McLeod tartan, his birthright, but claims to own "a lot of McLeod things", with a vague wave of his hand. It is evidently his sister, a senior US judge, who keeps the family connection alive by visiting Lewis every year. Trump has promised to stop in his ancestral home soon, but can't say if he will invest there too.

The phone rings. Would I mind if he takes it? His daughter in California is worried about forest fires. "Well how far away is the smoke? I'll buy you another house if it burns down, honey, OK?"

Trump hasn't seen Local Hero, but he knows enough to reject the comparison. "From what I understand, it wouldn't apply to me," he says, "because everybody in Aberdeen, 10 to one, is in favour of this job. This is a very popular job, and that's the difference between this and the film, as I understand it. People would be extremely disappointed if it didn't get approved."

This is Trump world, a relentlessly positive place where no weakness is acknowledged, no opposition allowed for. To hear him talk about the development, one would think that his bulldozers will be greeted with garlands of heather.

He says: "I'm going to spend $1.5 billion building something that will be the talk of the world. Everybody wants this to happen. It will be great for the economy, will be great for tourism, will create a lot of jobs. It's 134 letters against, over 2000 letters in favour. They want it very badly in Aberdeen."

He has hired Martin Hawtree to design the course, as much for his connections within the Royal & Ancient as for his design pedigree, which includes notable alterations to the links at Carnoustie and Royal Birkdale.

Trump is a good golfer himself, with a four handicap he is struggling to maintain as he gets older. So, Michael Forbes refusing to sell is like an unlucky kick into the gorse bushes, I suggest. "No, this is very easy," he replies. "It's not much of a problem."

What about the locals taking to the dunes with signs that say: "Dump Trump"? Might we compare them to a tricky pot bunker that he has strayed into with his approach shot? He shrugs off the analogy: "It's literally a few people, but they get all the press."

At this point the conversation is interrupted by the arrival of a party of Trump's friends. "This is Phil Rosen, the biggest lawyer in New York," he tells me. Rosen is here to shoot a short video for his son's Bar Mitzvah. The script is a pastiche of Trump's hit television show, The Apprentice. It ends on an uncharacteristically upbeat note: "Isaac, you're hired."

Once he has mugged his way through the scene, coaxing his adolescent co-star along like a true pro, Trump offers to show us the set. The Apprentice is in its seventh season, now with celebrities competing for his approval, a twist that undermines the programme's aspirational appeal. The mocked-up conference chamber and meeting rooms occupy a whole floor of Trump Tower, complete with ceiling-mounted cameras, two-way mirrors and microphones in the walls.

Trump's daughter Ivanka, herself a star of the show, joins us on the set. Trump introduces me: "This is Andrew, he's going to write a bad story on me. I can tell it's going to be bad because of his questions so far. But you know, I'll get over it, I'll keep going. Who else has had more bad stories written about them than me?"

The marriage of menace and charm plays into his capitalist anti-hero image. His catchphrase is: "You're fired!" He tells me proudly that it came third in a poll of the best-known lines on US television. I ask him what the first two were. "The top was, Here's Johnny' - you know, Johnny Carson," he says, "and that moon thing, which I don't understand why it's in there. One giant leap for mankind.' That's not a catchphrase, he only said it once."

Trump is accustomed to getting his way, and the occasions when he was thwarted have been expunged from his personal history so thoroughly that, to him at least, it is as if they never happened. He famously flirted with bankruptcy in the early 1990s, but managed to reduce and restructure his billion-dollar debts, before embarking on a fresh wave of accumulation and publishing another instalment of his best-selling business books: The Art Of The Comeback.

How much Trump is worth is a matter of considerable debate. He is, by any standard, a phenomenally wealthy man. But he does not actually own many of the buildings that bear his name. Rather, he acts as a consultant and front man, lending his brand to investments made my other developers. Last year he sued unofficial biographer Timothy O'Brien for calculating his net worth at around $200 million, describing his book, TrumpNation, as "badly written irresponsible, malicious and false reporting".

Forbes Magazine estimates that he is the world's 314th richest person, with assets of $2.9 billion - poorer than Richard Branson, George Lucas and Steven Spielberg but richer than David Rockefeller Sr, Gordon Getty and David Sainsbury. "I build great projects," Trump says. "And the community embraces us because they know that if Trump comes in it will be the highest quality development. You'll see that in Scotland. Ultimately it's all my money. I may finance it, but it's my money.

"I've faced opposition like this many times, and in all cases I've succeeded. Trump World Tower is the tallest residential building in the world. Everybody opposed me, I ended up winning. It's now one of the most popular buildings in New York and is receiving phenomenal reviews architecturally."

He views the environmental objections of Scottish Heritage and the RSPB as a hurdle to be cleared, no more, and insists that the Balmedie development will both stabilise the dunes and bring an end to hunting on the land, joking that "all we're going to be shooting is birdies and eagles".

"It's an extremely expensive project to build, and our environmental concerns have made it more expensive," he adds. "What we're going to do is to make it better environmentally than it is now. We're very sensitive to it. It's much more expensive to do that and not rip everything apart, but we feel like we have to do it."

He reaches for a copy of his book and writes on the flyleaf: "To Andrew. Treat me fairly!" My time is up. On the way out, past the endless portraits of success personified, I search for a declaration befitting this modern king of kings, in all his hubristic glory: "Look on my works, ye mighty, and despair!" But the Trump Organisation has no Shelley on its staff. There is only a small wooden plaque with a simple message. It reads "Donald Trump: You're Fired!'"