IT ALL began with an American dream. Sam Wanamaker, the actor and director, came to England looking for Shakespeare. Where the Globe Theatre had once stood, he found a parking lot marked "sold for redevelopment". Stratford-upon-Avon did its bit to keep the flag of Shakespearean performance flying - Sam had played Iago there in 1959 - but nobody had thought to recreate the wooden O so central in Shakespearean history. Suddenly Sam was a man with a mission - to rebuild the Globe. And not just any old wooden O - that had been proposed before, in the 1930s, during a vogue for half-timbering - but the great Globe itself, as true in every peg and joists as it was possible to be to eye-witness impressions and rough contemporary sketches.

It was a Herculean labour, which turned Sam himself into a bit of a hero. Not only did he have to raise the money to build his replica Globe in the armpit of the Thames that is present-day Southwark, but he had to convince a phalanx of academics and a regiment of theatre professionals that it was not simply an exercise in heritage kitsch. It took a life-sapping 25 years, and shortly after the building began, he died.

That was three years ago, and since then a huge edifice has reared up in Southwark. London is not a city of surprises - its history is well-tended and predictable. And Southwark is a particularly odd borough - queasily stretched between the regeneration chic of riverside shopping malls and the ersatz historicism of the London Dungeons. Where there were bear pits and brothels, now there are railway arches and newspaper offices. Nothing prepares you for the shock - after a taxi ride over Southwark Bridge, round a half-hearted one-way system on to bumpy side streets - of arriving at a sheer brick wall among puddles of people in cagoules bearing clipboards.

Walk in through a foyer carpeted in the same hard-wearing beige as dozens of civic centers and, suddenly, there it is. The wooden O. The great stage, flanked by its two huge pillars, is still a working model in grey plywood. But the main beams are of a monumental oak that already seems to be splitting and silvering with age and symbolic importance. This is a building that groans with a heroic enterprise, quite distinct from whatever Othellos or Lears may one day thread its boards. It compels you to think in terms of dynasties, tradition, heirs. It is, of course, entirely artificial. The original was a fire-trap and, as Christopher Ricks pointed out recently, a breeding-ground for the Plague that terrorised Elizabethan England. The new Globe's thatch is topped off by a little rows of fire sprinklers.

So why is this architectural fantasy so moving ? It occupies a unique position in English culture, because of the unique status accorded to its dedicatee. William Shakespeare is a secular patron saint : he comforts the English-speaking world with a sense of its solidarity and its superiority. He is our most successful diplomat and a one-man tourist trap. His plays have been built so deeply into the foundations of our education system that every 16-year-old who survives the National Curriculum will have studied at least one. He is at the heart of our dramatic repertory - even Hollywood believes he was the original million-dollar man.

It is as if the Globe stands on a cultural ley line. Both physically and metaphorically, it is the place where three powerful factions confront each other. There are the academics, a formidable international brigade obsessed with analysing the Elizabethan experience as precisely as possible, who have bled the plays dry of their clues about the original staging but have no way of replicating the actual experience. "They fight a very vicious feudal war on the theoretical level, and that ethic is very difficult when you start to move into building things, " says the Globe's Artistic Director, Mark Rylance. "A couple of them who are closely involved have had to put their theories into millions of pounds of timber. "

Then there are the theatre practitioners - actors, directors and technicians - whose obsession, equally intense, casts the challenge of re-creation in a rather different form. They don't know how Shakespeare coped with this open-air barn, but they are sure he must have coped - because they are convinced he is a genius. Their problem is to reconcile this genius with the techniques of a theatre that has developed within the proscenium arch and the studio, with artificial lighting and microphones. A theatre which is struggling to communicate with audiences raised with a television in the living-room. They, too, have reason to be terrified of seeing their ideas set in timber : the Globe is the ultimate experimental space. If it doesn't work, is it the fault of the theatre or of the actors ?

Finally, there is the heritage industry, with its hunger for the picturesque, the sellable-in-many-languages, the play-of-the-film-of-the-T-shirt. The heritage industry is responsible for transforming Stratford into a theme park, yet it is only pursuing its own, partial, view of history - a view with purse string attached. Though the Globe has attracted set-up money from all over the world, it will have to pay its own way once it is running. The heritage industry - in the broadest sense - will, ultimately, foot the bill.

To see how entrenched the factions are, you need only look to last year's four-week workshop season, when actors, directors and academics were invited to try the theatre out and ended up fighting over such vital details as where on the stage those two pillars should stand. Peter Hall fretted that the mock-up was "frightfully wrong", while scholar Andrew Gurr thundered : "Peter Hall is operating on gut instinct and challenging the consensus of 120 international theatre scholars." In the end, the practitioners won and the pillars were moved. But ask an actor why, and you begin to understand the scholars' frustration. "It seems much warmer," says Rylance. "The old design created a sort of D. It seemed important to have a square in a circle, which is what Shakespeare talked about."

Rylance, 36, a brilliant actor, is an odd figurehead for an institution that - in time - should be among London's premier tourist attractions. Where you would expect a smart-talking huckster, alert to any marketing opportunity, you find a man who does not want to be a hero - so determined that the Globe be seen as a collective that he refuses to be interviewed by himself, although finding a time to interview three actors is three times as difficult as pinning one down.

This is the actor who, in one RSC season, played Romeo and Hamlet - Hamlet like Romeo and Romeo like Hamlet, as one critic remarked. His administrative commitment runs to mortgaging his flat to take a production of The Tempest to the Rollright Stones, where it was almost washed away. He is a slight figure, with a Wisconsin lilt and a rare quality of gentleness that - without being sexless- has more in common with Ariel in The Tempest than with Coriolanus. You imagine that as a boy he kept orphaned fledglings in shoe boxes beneath his bed.

Mark Rylance is perhaps the clearest embodiment of the theatre establishment's urge to understand its patron saint. There is even a certain recklessness in his choices. He won't be opening the Globe with a GCSE set text like Romeo and Juliet or a star vehicle like Macbeth. Instead, its first public season - or "Prologue" - will begin next Wednesday with the early comedy The Two Gentlemen of Verona. True to form, he leads from the middle as Proteus, one of the two gentlemen, in a production directed by a fellow actor, Jack Shepherd. "I wanted someone who put the needs of the players first, not some great conceptual director, " he explains.

OF COURSE his vision of the "true" Shakespeare is as riddled with supposition as all the others. He won't buy in household names to appeal to the charabanc trade - "if by big names you mean people from film or TV". Why not ? "Because it's like the difference between being good at hockey and ice hockey. I went to see Al Pacino doing American Buffalo and he didn't have a chance, because everyone clapped when he came on. I want a proper ensemble. Not people who come in for a few performances."

But wasn't Edmund Kean as big a star as Pacino in his time ? Aye there's the rub. Rylance admits that Kean would probably have wafted in for three or four command appearances, like a big opera star today. The modern Globe actor will be expected to work a taxing nine-show week, without even the sanctuary of a private dressing room : no hierarchy, so no star dressing rooms. How much of this jolly communality is Shakespeare - a canny impresario as well as a theatre craftsman - and how much is Rylance, a fey visionary who has not yet been confronted with the demands of maintaining an institution like the Globe ?

His first few months have certainly brought him face-to-boot with the bruising realities of being custodian to a legend. Suddenly, the critics' darling seems to have become public enemy number one. Last summer, he both directed and starred in a production of Macbeth that had men reaching for dictionaries of abuse. The production had an idea about popular religious cults that seemed to do with a slightly unfocused curiosity than with dictatorial zeal. When it opened, it was seen as a proof that Rylance was unfit to guard Shakespeare's reputation : "The Globe is already in trouble. If Rylance offers work like this, we can forward to a fiasco of monumental proportions," snapped the Daily Telegraph, while the Times critic made a pledge to eat the First Folio complete if the next decade produced a more ill-conceived version.

"I was trying to do something very difficult," admits Rylance, "which was to direct a play at the same time as starring in it. The risk is that you don't allow yourself enough time to work on your own performance. But we don't do things carelessly. People seemed to be more horrified than my production could have justified." For explanation, look at the chronology. When he began working on Macbeth he was a very much-loved oddball - "a DIY exotic". By the time it opened, he was Mr. Globe. Overnight, the stakes changed. Greenwich Theatre, which is usually underwhelmed by attention, became the venue of the week.

The hostility surfaced again last month when Rylance decided to abandon a Shakespeare prize set up in the Globe's name by Wanamaker. The judges, who suddenly found themselves without a judging panel, were outraged. Several were critics and they committed their outrage to print. Zoe Wanamaker - Sam's daughter and a board member - was approached and said she knew nothing about it (in fact, says Rylance, she had missed the vital board meeting).

"I was naive," he admits. "I didn't realise people felt so strongly. To me it felt divisive that we honoured individuals, but gave no recognition to the people who make outstanding costumes or formed the ensembles. The men who have played Benedick have always won prizes - but what about the women who play Hero ?"

What will he do ? "I'll take them out to lunch to explain, " he assured me. A week later, he was back at the stake in the trade newspaper The Stage for not wanting to give critics free review tickets. "I can't find any authentic evidence of critics receiving free tickets and glasses of wine when they came to do their job," he declared in the Globe newsletter. So, it seems, he is more Feste, the witty fool in Twelfth Night.

He may be right historically and ethically, but politically he's breaking all the rules. Just by accepting the Globe's mantle, he has entered the political arena where - as any Shakespearean king could tell him - pure ethics will always have to be tempered by statesmanship. But what, in Globe terms, is statesmanship ? Is it, as Rylance would have it, leading a quasi-mystical quest for the true spirit of the bard ? Or is it - more brutally - having the nous to keep peace between the clans laying claim to the Shakespearean heritage ?

At the moment, he's in a position of confidence. The Prologue season has already paid its way through visits and tickets sales. But what if, next summer, it rains every day and the groundlings, who pay to stand in the open air, stay away ? The Globe will have at least 2,000 tickets a day to sell once both the main theatre and a second auditorium, the Inigo Jones Theatre, are running. What if the scholars come up with irrefutable evidence that we've got it all wrong ?

Rylance's unwordliness may yet turn out to be his trump card. He has called this first season the Prologue, in acknowledge that everything may yet change. Only when it is over to everyone's satisfaction will the great stage be built in solid oak. And what if it is still not right ? Rylance's face splits into a boyish grin. "If it turns out that it's the wrong way round, then we'll raise the money to turn it round." Now that really is Shakespearean : it's Feste's wit crossed with Hotspur's heroism and the pure mischief of Puck.