Oracle - Biosphere 2

5mi south of Oracle is the giant glass structure known as Biosphere 2, an artificially created, self-maintaining habitat in which four women and four men lived from 1991 to 1993 completely shut off from the outside world, wholly dependent for air, water and food on the productive capacity of this artificial miniature world. Seven "biomes" (tropical rain forest, savanna, desert, lagoon, coral reef, mud-flats, shallow sea, deep sea with poor light) in which over 3500 species of plants and animals were established helped to show that human beings can live a healthy life without destroying their environment.

The project, financed by the billionaire Ed Bass and directed by the scientist John Allen, is planned over a period of a hundred years. Every two years a new team is to inhabit the "biggest test-tube in the world".