The wizard from Oz

With his shaven head and sunken eyes, architect Barrie Marshall looks as grizzled as the outback landscape of his native Australia. He is exhausted, still suffering from the 19-hour flight to England and the continual trekking he has done around the site of Stonehenge. "I'm getting to know every blade of grass on Salisbury Plain," he says with a weary smile.

The 55-year-old is here to learn about the prehistoric stone circle and develop the ideas that won him English Heritage's competition to rethink public access at the world heritage site. In April, the firm he co-directs, Denton Corker Marshall, made a pitch persuasive enough to knock out home-grown architects, including Michael Hopkins, Birds Portchmouth Russum and Allford Hall Monaghan Morris.

It was an astonishing coup for a firm that, despite winning a gold medal Down Under, has yet to build anything in England. The man from the New World admits that it seems odd that a firm specialising in eccentric skyscrapers could have won the work on one of Europe's oldest monuments. And it is especially impressive considering the 25-year saga to improve facilities has seen the collapse of detailed schemes by British heavyweights Edward Cullinan and Sidell Gibson.

But this latest effort is different. This time, EH asked the architects to come up with a concept rather than an actual building design. "We had a beauty parade and Barrie Marshall absolutely breathed magical understanding of Stonehenge," says Sir Neil Cossons, chairman of EH.

"What we wanted was somebody who could bring an approach to the questions set out in the brief. He had a deep understanding of what the building should be doing, but without an immediate translation into an architectural form."

As for the Australian connection, Marshall managed to turn that to his advantage. Cossons likens Ayers Rock to Stonehenge, and comments: "He was extraordinarily understanding and eloquent about what Stonehenge meant, the way that somebody from the opposite side of the world might well be."

Marshall's plans are at an early stage – site size and budget are still unknown – but his broad vision is clear.

"The key objective is to return the stones to the setting they really belong in – to redefine their relationship with the landscape without cluttering it up with other buildings and roads," says Marshall.

I’m getting to know every blade of grass on Salisbury Plain

"Though it's such a sensitive site, what we're proposing makes us feel comfortable because we are not adding a new piece to the composition."

The present visitor centre is a concrete box that squares up to Stonehenge from across the busy A303. This will be demolished and a new centre built on a site 3 km away, outside the world heritage zone. Once again, the monoliths can stand apart from alien architecture.

The highway, which at present, sends cars zooming within metres of the stones will also go, sunk underground for nearly a kilometre.

It is hardly surprising that this approach got the nod from EH, but it may seem strange that Denton Corker Marshall was chosen to pursue it, given its back-catalogue of ostentatious architecture.

The firm has built extensively across South-east Asia and Australia, and has offices in Sydney, Jakarta, Hong Kong and Ho Chi Minh City that employ more than 200 staff. The work is often subversive – in keeping with the "ratbag" identity co-director John Denton uses to describe the firm.

It is hard, for example, to see how work such as the hallucinogenic Melbourne Gateway or the Governor Phillip Tower in Sydney (which Tom Cruise's character parachutes out of in Mission: Impossible 2) can be reconciled with a need for sensitive, low-key architecture.