Meanwhile, with the opening of an exhibition in Greenwich town hall describing the plans, the murmurs of doubt about the wisdom, cost and direction of the pounds 700m-plus project grow louder. Why has the projected cost already jumped pounds 200m? What will Rogers's vast dome be for? How can a plastic roof, however huge, cost half a billion pounds? And (looking nervously over our shoulders) why is it that we are doing so much to mark the millennium when most other countries are apparently doing little or nothing?
Last week the Opposition pitched in with its own dollop of scepticism when the Shadow Heritage Secretary, Jack Cunningham, wrote to Virginia Bottomley questioning the income projections for the scheme, the lack of budgeting control and the absence of a hard figure for the commitment an incoming Labour government would be expected to meet. Labour was said to be particularly disturbed by a risk assessment that suggested the exhibition could exceed its pounds 700m costing by pounds 400m. There was speculation that Labour might be bracing itself to jettison the project altogether if it comes to power. On Friday, Barry Hartop, chief executive of Millennium Central, the quango responsible for the exhibition, unexpectedly announced that he was stepping down.
Against this threatening backdrop, Lord Rogers spoke for the first time last week of his vision of the Millennium Exhibition and why he believes it is a worthwhile endeavour for the nation to support.
Outside his office in Hammersmith, mist clung to the poplars, the Harrods Depository looked like the relic of an abandoned civilisation and, on a Thames stained orange by the wintry sun, a single skuller and a small cacophony of gulls offered proof that the world had not come to an end - but pretty meagre proof. Anyone who disputes Rogers's view that the River Thames is London's most under-used asset need only peer out of his office window for confirmation.
Rogers is one of our two most famous architects, along with his former partner, Sir Norman Foster. Foster is much more prolific than Rogers, but Rogers's two most famous buildings - the Pompidou Centre and Lloyd's - can claim a far stronger purchase on the non-architect's imagination than anything Foster has done. And Rogers - tall, courtly, perennially tie-less, an elegant bundle of passions and enthusiasms - is one of the great movers and shakers in our cultural life. He slides readily and smoothly from the role of architect to that of planner, dreamer and prophet, in a way that none of his British contemporaries even attempts. If, as is persistently rumoured, he is given ministerial rank in an incoming Labour government, he will at least have no shortage of things he wants to do.
Rogers's millennium plan envisages a monstrous dome, big enough to enclose two Wembley stadiums or 13 Albert Halls, the biggest dome in the world, to be built on the tip of the Greenwich peninsula in east London, a 300- acre knob of land north and east of historic Greenwich and across the water from Canary Wharf and the other new office buildings and housing developments on the Isle of Dogs.
At present the peninsula has little going for it: owned until recently by British Gas, and used for gas storage, it is heavily contaminated and lacks infrastructure of any sort, even electricity and drains. Before the dome can be built the land will have to be decontaminated and the basic infrastructure installed. That expense accounts for a great deal of the cost of the project - Rogers says that the building itself, the "tent" or "umbrella" as he likes to refer to it, will consume only 3 to 5 per cent of the development cost - some pounds 30m. But the installation of this infrastructure is the underlying justification for what would otherwise be a reckless frivolity. Once the year-long millennium party is over, the Greenwich peninsula will be ripe for permanent, long-term development.
The Greenwich peninsula project is most readily understood in the larger context of Rogers's grand plan. "The most beautiful thing we have is the Thames," he says. "I want to make that once more the heart of the life of London, rather than turning our backs on it, as has happened since industry has not been able to use it.
"The concept we developed was beads on a string - or pearls on a string, depending which party you come from. What we need to do, we said, was build up a series of urban nodes along the river, most of which already exist: strengthening existing ones, creating new nodes, all of them adding up to an overall hierarchical system."
What exactly are these "nodes"? "Nearly all the crucial monuments in London are along the river: the Houses of Parliament, St Paul's - which is a couple of hundred yards away - the Tower of London, going all the way down to Kew if you like." But there are modern nodes, too, most obviously the South Bank arts complex, which Rogers wants to enclose in a great undulating roof. "If you build up density points," he goes on, "you create desire points, too. Over the next 10 years, the South Bank could potentially become the greatest cultural centre of the western world, in my opinion."
As Rogers sees it, these new urban nodes, these desire points, "go from the renewed Battersea power station to the Ferris wheel opposite the Houses of Parliament, to our own South Bank centre development, to the new Tate at Bankside, the Globe, the Oxo Tower restaurant ... The point I'm making is that these are new centres. Our idea was to link these beads or pearls. This idea was developed before the millennium project came along, and at the time the Greenwich peninsula was just an ordinary bead like the others. But the millennium gave us concentration, and then Greenwich became a major bead, the crown or the clasp in the string of beads, because Greenwich is the gateway."
The antecedents of the Greenwich project are obvious enough: the Great Exhibition of 1851, and the Festival of Britain, 100 years later.
"When they're good, exhibitions can be of great economic and social advantage. I suppose the greatest one we had was the Great Exhibition of 1851, which first announced to the world that we were the most advanced technological country. What it also did was to leave in London an amazing development from the V&A up to the Albert Hall - and money left over from that time is paying for people who are still going through university. It's a terrific legacy.
"A modern equivalent could be Barcelona's Olympics, which had a wonderful advertisement: `The Olympics and 150 new squares' - in other words, not just the Olympics but a great public domain. Barcelona has now become the exemplary town in Europe if one wants to see how an historic town has coped with the end of the 20th century. It retrieved miles and miles of beach full of old and now useless warehouses, typical of any riverside, and turned them into the most stunning restaurants, housing, parks, offices, yachting harbours. They had the most enlightened mayor, and a very good local minister of culture, and they left a great heritage."
The Greenwich peninsula could, Rogers insists, benefit in similar ways. "It will have all the elements of an ordinary town: a very good tube station, 15 minutes from Trafalgar Square, the riverside, a great walkway along the edge of the water, a park all the way through the centre with a lot of trees, and offices, housing and shops. It will be a sustainable development which is all about people living, sleeping there, people working there, having leisure and culture there - in other words, a community. The exhibition must have the potential for social and cultural regeneration: the Los Angeles Olympics may have balanced the books, but they didn't regenerate Los Angeles. To make it of use it has to be regeneration by which the poor are advantaged as well as the rich - it has to be an inclusive celebration. The Greenwich site is a linchpin between all sorts of areas that are very fragmented. The whole focus of what we are doing is seeing how you make new parishes."
In his tireless evangelism for planning, Rogers is true to the eternal verities of his profession. But whether this means that he also knows what makes London tick is another matter. London's "critical monuments", as he puts it, may be concentrated along the river, but none of the new ones has yet lived up to its apparent potential . Forty-five years after the Festival of Britain, the South Bank arts complex, for example, is a fine, heavily subsidised concentration of music, art, theatre and film.
But as a zone of London it stubbornly refuses to come to life, and a walk along the river from, say, Hungerford Bridge to the revamped Oxo Tower is a dispiriting experience.
Rogers's answer is to roof the place and give it the climate of Bordeaux - but arguably that's beside the point. The public bits of London that really work do so in defiance of the weather; places like Camden Lock market, Covent Garden or Brick Lane, all of them largely exposed to the elements. Europe's greatest modern artistic renaissance has occurred in the post-industrial desolation of the East End; its annual celebration takes place in the shell of Spitalfield Market. Erupting in the aftermath of planning failure, inhabiting the neglected interstices of the city, these phenomena are joyfully parasitic on the capital's crumbling monuments. Their presence, and their energy, is the opposite of planned: in spirit, they squat.
The main difficulty one has with the Greenwich peninsula scheme is not the question of what will go inside it, nor with the underlying notion of throwing a party for the year 2000; it's that, though round, his dome is actually square. Harking back to Crystal Palace and the Festival of Britain's Dome of Discovery (which it slightly resembles), it belongs in spirit, like most architects' grander conceptions, to an age when architects enjoyed a level of respect which they forfeited long ago.
London's success and current vogue, despite the absence of planners, mayors and the rest, is because it is a splendid old edifice of a city which highly creative people deem worthy of occupying, of adapting and transforming in a manner that is usually haphazard, in the teeth of plans and planners. Given the right sort of access and incentives, these sort of people could probably work wonders with the wasteland of Greenwich peninsula, too. But whether they could find any mode of coexisting with Lord Rogers is open to doubt.