We can expect a proper celebration now that Blair's government has given the green light to the Greenwich Millennium Exhibition and its spectacular Dome

This is what all the fuss is about - the architects' and designers' vision of the inside of the Millennium Dome at Greenwich, designed to celebrate British genius. Who knows what the original sketches of the Hanging Gardens of Babylon looked like, or the rough drawings of the pyramids? They were built because of political vision and a commitment to art. Now Tony Blair's legacy to the nation will be the greatest exhibition centre in the world, on reclaimed land at the Greenwich Peninsula. Building work on the world's largest dome, designed by Richard Rogers Partnership to be strung from pylons and radiate a forest of lasers by night, begins next week. On 1 January 2,000 visitors will be able to take a boat ride or the 15-minute tube journey on the Jubilee Line extension from Trafalgar Square to Greenwich to open their eyes to the 21st century.

Inside, Rogers explained yesterday, visitors will have the chance to interact with scientists in a big auditorium beneath the dome; experience the Big Bang in a multi-media show staged in a 10,000-seater auditorium and take a virtual reality safari through the human body. There are plans to use voice-activated electronics in a 21st century version of the Domesday Book as visitors record their own brief lives; products that show British genius and a chance to "Build Your Own Britain" on the net with electronic images of the earth beamed from Nasa into schools around the country. As for the home of the future - no more trudging off to Tudor-Bethan suburbia at the Ideal Home Exhibition because it will all be here.

When Richard Rogers Partnership designed the Pompidou Centre in Paris with Renzo Piano, they learnt that a good building can turn into a mega-tourist attraction. But what they failed to with Greenwich, hence all the brouhaha, was reveal storyboards of the contents and the interiors earlier - even though it wasn't their job. Besides, their priority was to get the building off the computer. Yesterday all was revealed at a special presentation to the Cabinet at a document headed "Why your children would want to visit the Millennium Dome."

All the infrastructure - canals, walkways, tube and bus links - has been master-planned on site for the long-term future by Richard Rogers Partnership with English Partnership, owners of the site, but even the ebullient Richard Rogers slogging it out with soundbites on the news every night this week must have had some doubts.

With the Cabinet's proviso yesterday to make the contents more exciting, and its requirement for more detailed information of what's inside, there are going to be shake-ups. It also stipulated that the exhibition must be durable and last forever, knocking on the head all the moans about a great white dome costing billions being pulled down after a year. This misunderstanding arose because the Millennium Commission can only give away lottery money for projects celebrated in the year 2000. It doesn't mean that in 2001 everyone just picks up the tent pegs and steals away to leave a great empty site like Expo '92 in Seville. It could be sold to sponsors or become a national monument, a sports stadium or a theme park.

For the record, the architects cut the cost from pounds 780m to pounds 580m with the site, buildings and infrastructure budgeted at pounds 215m, the dome at around pounds 40m, the contents for pounds 230m, and the operations costs at pounds 145m. To pay for that they were granted pounds 200m from the Millennium Commission, and are counting on pounds 195m from gate receipts and pounds 195m from sponsors. Wouldn't it be pathetic if Britain can't find 65 companies with pounds 3m to spend on their image or on promoting products worldwide in the next century?

The Treasury wasn't short of know-it-alls to tell them how to spend the money if the project had been cancelled. Richard Branson said "let's spend the Millennium money on health, education and street parties", quite forgetting that the Millennium Commission can only give money for projects that celebrate the big moment in the year 2000. Millennium money is celebration money and what a celebration we can anticipate.