Now the bridge, hailed for its revolutionary "horizontal suspension" technology, is having to close for more structural work.

Reverse measure - the Lloyd's building

It is a serious blow to the high-profile project, which had already fallen behind schedule. It will also stir up tensions in the simmering debate over modern architecture.

Try as they might, traditionalists will find it hard not to raise a wry "told you so" smile at the setback.

From the start, Sir Norman Foster, the bridge's designer, emphasised its innovative nature.

The objective was, he said, "to push [suspension bridge] techniques as far as possible to create a uniquely thin bridge profile forming a slender blade across the Thames".

It sounds great, and on paper probably looked sublime, but often reality is the harshest judge of cutting-edge architects.

Two years ago, the celebrated British architect, Lord Rogers, paid a heavy price for his iconic 1980s creation, the Lloyd's of London building.

Covered in netting, the Bastille Opera House was compared to Ena Sharples

Lord Rogers - together with engineers and builders - paid �12m to cover the cost of repairs to the towering glass and steel landmark.

Initially applauded for its radical "inside-out" design - service pipes and other usually hidden features were clamped to the outside of the building - it was later struck by corrosion. Remedial work took 18 months to complete.

Lord Rogers was in the firing line again after revolutionary glass supports in his �27m law courts building, in Bordeaux, France, shattered a week after completion.

The French penchant for modern architecture has led to other notable fiascos.

The 1980s Bastille Opera House in Paris had to be shrouded in netting because of loose cladding and, last year, a new bridge across the Seine was closed immediately after it opened following problems similar to those experienced by the Millennium Bridge.

Troble at the drawing board

National Theatre, London - discolouration and leaks Waterloo International - glass panels dislodged Dept of Environment HQ - glass louvres rattle in wind

Yet they rate as nothing compared to the blushes over the new national library. Only after four all-glass structures were finished did it occur that storing sacred texts in broad daylight was probably not a good idea. Blinds had to be added to the higher stories.

David Taylor, deputy editor of Architects' Journal, says there is a price for experimentation.

"You do not progress as architects and engineers without a certain amount of pushing the envelope," he says.

Others say if architects and engineers had more time, problems could be rectified on the drawing board rather than on site, after opening.

Legal issue

Tony Chapman, of the Royal Institute of British Architects, says builders and architects have always had to contend with teething troubles. Today it has become a legal matter.

Waterloo International, where moving glass panels became dislodged

"Once upon a time, these things were repaired and no-one was any the wiser. But because we have inherited this culture from America that someone is always to blame, these things have become much more of an issue."

Indeed, architects have always had to contemplate failure and humiliation. In Paris, the Gothic style of the 12th Century allowed higher and wider buildings, with more glass.

But in Beauvais Cathedral, the architects over-stretched themselves with their ambition to build the tallest vaults in the world. In 1284, the choir collapsed.

Perhaps the most distinguished architect of the 20th Century, Frank Lloyd Wright, was unapologetic about his reputation for leaky roofs. "That's how you know it's a roof" he retorted to one client.

Computer model

While architects have always used scale models to test new designs, today they also use computer modelling to work out the complex mathematics involved in radical engineering and design. Might they be too reliant on the micro-chip?

Shattered dreams: The new Bibliotheque Nationale in Paris

Mr Chapman thinks not, although he agrees computer tests do not necessarily take into account the "human experience" of visiting a real building or bridge.

The British have long had an uneasy relationship with modern architecture. David Taylor concedes this might explain why insiders are defensive when it comes to admitting there is a downside of new design.

Reflecting on his troubled Millennium Bridge, perhaps Sir Norman Foster should take comfort in Frank Lloyd Wright's view of the job.

When he designed his Falling Water house, Lloyd Wright was told by many the cantilevered concrete structure was unworkable - if not physically impossible.

But he went ahead regardless and constructed what has since been voted the best all-time work of American architecture.

"The architect must be a prophet," said Lloyd Wright. "A prophet in the true sense of the term ... if he can't see at least 10 years ahead, don't call him an architect."