Next week, the Architecture Foundation is launching `London Interactive ', the first ever digital exhibition of the capital's best modern buildings. From computer terminals visitors will be able to float across the city taking in spectacular views at the click of a mouse. By Ian Burrell
It was in Richmond, south-west London, that the fictional time-traveller of HG Wells's imagination first devised an elaborate contraption made from ivory, brass and quartz with a series of levers to transport him between the past and the present.

Now, 102 years after the publication of The Time Machine, a team of modern- day adventurers working in an office above a pub a mile or so from the home of Wells's anonymous inventor, has developed a remarkable digital interactive computer system which takes us a step closer to the dream of travelling through time.

One moment you could find yourself sat aboard the revolving carousel of the as-yet-unbuilt Millennium Wheel, gazing out at the cityscape of 21st-century London. Then, seconds later, you could be a decade back in time, pacing the floor of an art gallery which no longer exists, viewing an exhibition which you never got round to seeing before.

An insight into how we may soon inhabit such virtual worlds will be revealed on Monday when Culture Secretary Chris Smith opens an exhibition at the Architecture Foundation, which will make this interactive system available to the public for the first time.

From a series of computer terminals, visitors to the exhibition will be able to float across eCity - the electronic city of London stretching from Kew in the west to the Royal Docks in the east - targeting buildings of interest, like a Luftwaffe bomber during the blitz.

Entry can be gained to locations normally inaccessible to the public. Once inside the Lloyds building in the City, the traveller can move easily from floor to floor, touring the offices, inspecting the facilities and admiring the views.

Countless photographs, taken from within the building, have been seamlessly stitched together using computer software to give a virtual panorama, controlled by the mouse on your desk but realistic enough to make you think you are actually inside Richard Rogers's famed edifice, spinning around amid the frenzied financial activity before you.

The technology for the exhibition has been developed over the past two years by Hayes Davidson, Britain's leading firm of digital architects. Based on a series of high-resolution aerial photographs taken by the Leicester company Wildgoose, the program uses the drawings and photographs of architects and designers to create realistic 3-D images of buildings and their interiors.

Hayes Davidson's 12-strong team now have images of some 150 prominent London buildings which can be input into the program. Alan Davidson, the company's director, says that the potential is enormous.

"I am sure that within 50 years, all the significant communities and capitals of the past will have been created virtually.We can replicate what is there now, as we have done with eCity, and the real potential is for being able to explore possibilities for the growth of the cities of the future."

The eCity could, in time, allow prospective housebuyers to view all the properties in their chosen district and price range without leaving a desk, using the digital images supplied by estate agents to move from room to room around each house.

Local schools could similarly be identified and toured. The program already includes details of the public transport infrastructure, and it should be possible to trace in pictures of the journey home from work and the walk from the station or bus stop.

Art galleries, as well as offering a virtual panoramic tour of the building, could display images of the artwork shown in current and past exhibitions. Designer clothes stores could give virtual previews of new collections.

The Hayes Davidson technology can also take the traveller into the future by creating 3-D imagery of buildings which have yet to be built. The Millennium Tower and the Tate Gallery of Modern Art at Bankside have already been finished. The team has also digitally created a vision of how 21st-century London might look after incorporating an extra two billion square feet of office space, leading to a forest of high-rise towers south of the Thames to rival those in the Square Mile. Davidson says that the information contained in the program was too much to be transmitted down a telephone line on to the Internet.

In the meantime, there are plans to make the eCity - and similar models of other areas of urban Britain - available at fixed locations such as libraries and town halls.

Davidson says that the digital technology should help to reduce people's fears over future building developments. "It avoids the suspicion that is sometimes associated with sketched drawings," he says. "Because it looks real, it contributes to a healthier debate."

The public availability of the program, he says, could contribute to greater democracy in local planning. "We might allow people to vote on which design approach they preferred, using real images instead of having to go to a dusty planning department. There has been a lot of good design which never saw life because it seemed slightly frightening drawn in the conventional way."

The Architecture Foundation's exhibition, which is called London Interactive, will be the first stage of this grander plan to increase the availability of the eCity. Based at the foundation's headquarters in Bury Street, near Piccadilly, it will feature 74 London developments which have been built in the past decade. The sites range from the Oxo Tower restaurant, the ITN building and the Saatchi Gallery, to Piers Gough's public lavatories in Westbourne Grove, Notting Hill.

The driving force behind the exhibition is the dynamic young director of the Foundation, Lucy Musgrave, who says it formed part of the charity's mission to encourage greater public involvement in the built environment and a wider appreciation of good design.

Musgrave compares the exhibition site to an Internet cafe and says she is looking for a wide cross-section of visitors. "I hope it's going to be really exciting. You can play God for half an hour and, hopefully, it's going to be very empowering. You can move over London, focus in on streets and go through buildings."

The exhibition is part of a larger programme, which incorporates a series of public roadshows across the capital, aimed at involving people in the debate on issues such as public housing, homelessness, green spaces and public transport systems.

"The reason we are doing all this is that we think it's absolutely crucial that the professions - planners, architects, engineers - start to do more to engage with the public and to demystify all this jargon which is used in all this very important decision-making which impacts on people's lives," says Musgrave.

"If a building goes up on your street you may love it or hate it, but you are not encouraged to take part in the decision. Whether you are four or 84, you are an expert on the built environment. If the planners want to consider change, they ought to be talking to the people in the street about what it's like to live there." She says planners and architects need to take a more holistic approach to their work. "It's not just about what buildings look like. It's about `Where are the lungs, the green spaces? Where's the river? Where are the bridges across the river?' This model allows us to look at London as a whole, to raise those vital questions and unlock the debate."

London has been handicapped, says Musgrave, by not having had a single overall planning department for a decade, since the abolition of the Greater London Council. "Without a democratically elected strategic planning authority, the decisions have been made behind closed doors by experts working in one field without a wide holistic vision," she says. "But issues such as river pollution do not respect borough boundaries."

As well as involving a wider public in the planning of 21st century London, the London Interactive project is also intended to be an inspiration for Britain's younger architects, who, says Musgrave, showed "worrying similarities" in their work as they went in search of commissions. "We have not had a confident enough climate to ensure that people can experiment and express their own individuality."

The recent availability of Lottery money for building projects has created a new era of opportunity for young architects, and the exhibition is intended to show them what can be achieved by featuring some of Britain's finest established practitioners, including Rogers, Sir Norman Foster, Nicholas Grimshaw and Michael Hopkins.

The Foundation now intends to use plans for proposed London buildings as a basis for creating an electronic city for the year 2050. And half a century from now, future generations will be able to use the same kind of software to revisit the year 1997, touring our shops, restaurants, galleries and civic buildings.

"There is enormous potential for change," says Musgrave, "and by raising public awareness of good architecture and planning we can create cities which are more beautiful and sustainable places to live and work in" London Interactive is on permanent show at the Architecture Foundation, 30 Bury Street, London SW1, from 25 November. Open Tues to Sun, 12 -6pm.

Captions- Countless photographs have been seamlessly stitched together using computer software to give virtual panoramas of the capital (above), enabling visitors to `tour' the buildings and their interiors such as the new Tate Gallery (left) alongside the Thames at Bankside

Zooming in on the capital. From an aerial view (far left), we target the Lloyd's tower in the City of London and can inspect at will any part of the Richard Rogers building, including banking halls and even offices not normally accesible to the public. The computer technology has enormous potential for everything from house-hunting to visiting an art gallery without leaving home