Designed by Anish Kapoor – built by Kirk, Matt, Andy, John and Wayne

Standing nearly twice as high as the Olympic Stadium, the crazed, twisted steelwork of the sculpture that has variously been described as "Meccano on crack" and a "catastrophic collision between two cranes" is an undeniably impressive feat of engineering. More impressive still (whatever you think of Britain's biggest artwork) is the fact that it was bolted together by just three men armed with pointy spanners.

Come the 2012 London Games next summer, this scarlet monster standing between the the stadium and the Aquatics Centre will treat 5,000 visitors to views across the Olympic Park every hour.

The tower, officially named the ArcelorMittal Orbit, was designed by Anish Kapoor and Cecil Balmond and unveiled in March 2010. London Mayor Boris Johnson labelled it the "Hubble Bubble" for its resemblance to a shisha pipe, while one critic called it the "Eyeful Tower".

What can't be argued is the quality of the views it affords of the new Olympic skyline. With just the final fittings now being applied, its builders gave The Independent the first guided tour of the tower, from its base to the viewing platform 115 metres above east London. On a sunny morning, the panorama is spectacular.

The people to thank for the Orbit's complicated assembly are three "erectors" – foreman Matt Collier and his two assistants, Kirk Bilby and Andy Canning – led by construction manager John Calland and Wayne Heaton, a dimensional engineer.

They're a tight-knit unit, as you might expect of five men who had to live together in a house in South Woodford for the duration of the 10-month project. And it was a particularly challenging project, too; asked what his first impressions were on seeing plans for the Orbit, Mr Calland answers with characteristic dry humour: "What have I been lumbered with this time?"

"People draw buildings with gravity turned off," he says. "This structure's been made to look as if it wants to fall over – and that generally means when you're building it, it does want to fall over. We had to build it leaning north, because when you hang all the metal on the other side it pulls it over – it was a moving target at all stages." When attempting to make giant sections of metal weighing up to 60 tons connect in 16 places, with up to 10 bolts at each join and barely millimetres to play with, a moving target was the last thing they needed.

The team pay credit to the factory technicians who made the tower's parts, and the drivers of what Mr Calland describes as the "ballet of cranes" needed to hoist them up as its 35,000 nuts were tightened using special spanners called podgers. But for men whose steelwork on most building sites is later hidden away by exterior masonry, having their craft left open and on view to the world is a welcome change at the Orbit.

"It's fantastic, you can see everything," Mr Collier says, before deadpanning: "You can see can all the bolts that are untied..." There is a moment of nervous laughter from the tower's press officer before he smiles and reassures us they are fastened, really.

Mr Calland adds: "Here you can see all the steelwork, you can see how it stands up. And we've got the added dimension that this is supposedly a bit of artwork..." Supposedly?

"It's hard when you've been sat in a cabin 50 metres away from what you're building and all you're thinking about is getting the steel here, getting the paint on, making sure you've got the right bolts. I'm not here thinking, hmm, what a nice building." But he admits it does stand out after doing a run of shopping centres. "I don't go running back to Bluewater thinking: I've done this."

Engineers can sometimes resent the architects who get all the plaudits for ideas they have to realise, and one jokes: "I haven't seen Anish putting any bolts in." Yet they all seem genuinely enthused about what they have created. Plus they must all have some Olympic tickets as a reward, right?

At this question, the men don't look enthused – it turns out they had little luck in the workers' ballot for tickets. "Don't get me started," Mr Calland says.

"You got some tickets, didn't you, John?" says one of the erectors.

"Yeah, for the table tennis," he sniffs.

Elbow asked to call tune for the Games

The BBC's broadcasts of London 2012's sporting events will be preceded by a theme composed by the contemplative rockers Elbow, it was announced yesterday.

The band, whose latest album, Build a Rocket Boys!, was praised for its "heart-breaking melancholia", are perhaps an unlikely accompaniment for energetic sports but the band said they were "knocked out to be involved". Singer Guy Garvey added: "We have feelings of responsibility as we will be the soundtrack to so many images of personal sacrifice and endeavour while the nation roots for and celebrates with Team GB."

A spokesperson said the group had already started the production process, and that the six-minute track will be played for the first time next year.

Other BBC highlights for next year's Games will include the Corporation's biggest ever free music event: Radio 1's Hackney Weekend, and a new season of Shakespeare films.

Rob Sharp