The Earth Centre is a Millennium Commission Landmark Project and its first phase will open in May 1998. The centre is being built following an appeal by the UN's Commission on the Environment and Development for "vast campaigns of education, debate and public participation" in order to correct the course of present developments in the environment.

The Commission believes it is necessary ``to capture the hearts and minds of people young and old'' in the cause of sustainable development. And so do the organisers of the Earth Centre project. As well as being a global point of focus for sustainable development, the centre will be a world class visitor attraction that combines purpose with pleasure and is both inspiring and entertaining.

Showing in effective and dramatic ways why the growing pressure on the earth's natural resources makes sustainable development vital it will also seek the exchange of ideas to achieve such development. And it will promote universal quality and equality of life to enable people to develop their own potential.

''Sustainable development has been defined in many ways,'' says Sir Crispin Tickell, chairman of the centre's advisory board and the British Government's panel on sustainable development. ``My own definition is durable change for the better while protecting the earth that we inherit and the earth we bequeath.'' While showing that sustainable development is possible, the centre, ``above all, will provide a bridge between thinking about the environment and putting those thoughts into practical effect,'' says Sir Crispin.

On a 161.8 hectare (400 acres) site in a valley near Conisbrough, Yorkshire, northern England, and within two hours' travelling time for 17 million people, the centre is "one of the most promising tourism developments in Britain,'' says the English Tourist Board.

The Earth Centre is based on the belief that the environmental, social and other effects of current economic and industrial development are unacceptable and cannot be continued in the next century without the risk of "catastrophic breakdown''.

''We face the prospect of accelerating pollution of the global environment, man-made changes in the climate and in the chemical balance of the atmosphere,'' say the project organisers. They warn of over-exploitation of forests, oceans and other expanses and of grave threats to once self-renewing sources such as fresh water and soils. The centre will promote respect for the natural world, the conservation of habitats locally and globally, a reduction in the demand for non-renewable energy, renewable energy generation and the pollution-free manufacture of all goods.

It will encourage more repair, re-use, reconditioning and recycling. It is hoped that the centre's work will reduce international tension by encouraging worldwide understanding of and respect for different cultures, religions and ways of living and by the development of self-sustaining regional economies.

An important part of its activities will research many aspects of the environment, including sustainable farming methods to provide a wide choice of fresh foods, enhance the environment and respect animals. Organic farming will be featured and organically-grown food will be on sale in refreshment areas.

The Earth Centre, its imaginative and striking buildings designed by leading UK architects and engineers, will use less energy than other buildings of similar size. An impressively large solar canopy at the entrance and exit will be fitted with the biggest array of photo voltaic cells in Britain, producing 35 per cent of the centre's energy requirements.

Mechanical chlorofluorocarbon (CFC)-based refrigeration will be avoided in the air conditioning by using a system that retains night-time coolness for release during the day.

The first phase of construction includes the Planet Earth galleries which will present a series of "thrilling and powerful attractions to inspire humankind to work with the planet, not against it''. After a film show, visitors will walk through dark galleries of illuminated displays and messages which show the earth's bio-diversity and the threats to it. They will then move into a spectacular glass-roofed gallery which will convey the universal appeal of a sustainable future. The first phase will include other major attractions including Millennium Cities which will present creative visions of future cities from people all over the world, using projected images, sounds, light and models to leave the visitor excited about future possibilities.

Eco-Station is a combined indoor and outdoor attraction focusing on future sustainable transport. At 21st Century Living, interactive features will put visitors into the shoes of people of the future. A solar house will include the latest technology and examples of futuristic devices such as voice activated home appliances.

In another building visitors will also see how hydroponic plant culture is used in a water treatment system. There will be a children's play attraction and landscaped gardens.

One of the most important developments at the Earth Centre will be the opening in 2000 of The Ark, a vision of the next millennium presented under a vast glass roof which is one of the latest examples of "green'' building design.

The Earth Centre, virtually surrounded by eighty thousand trees, will have forty acres of gardens, walks and cycle trails, three play spaces and will offer river trips from its own wharf.

There will be a covered 400-seat arena in the design of a traditional Roman forum where musical, dance and theatrical events from many parts of the world will be presented. A 2,000-cover food and retail hall will include Britain's biggest ``green'' shop selling organic food and other items.

Here visitors will be able to put into practice some of the lessons they have learned _ because products for sale will include gadgets to help them contribute to sustainability by using less electricity at home.

And from the Earth Centre's inception its management team has considered the possible environmental impact of every aspect of design, construction and management of the project.

Even the land on which it is being built has been reclaimed from former industrial use - ``a visible symbol of the regeneration that the Earth Centre seeks to encourage, `` say the organisers.