It resembles a collection of radar domes, or a group of massive geodesic beehives that have fallen to Earth.
Rearing out of an abandoned china clay pit, it appears a frivolous addition to the fields of Cornwall, UK. But the Eden Project, which finally opens this Saturday, has a serious intent: to bring people and plants together.
Calling itself "a gateway into the world of plants and people", it aims to show how sustainable development depends on plants.
Humid zone
It hopes to attract 750,000 visitors annually, by becoming "somewhere very special that not only entertains but also encourages people to action, and provides the means for them to act".
Ways of encouraging action include linking schools around the world, and relating this educational work to practical projects, perhaps in rainforests or in local conservation initiatives.
The heart of the Eden project is three "biomes", each devoted to the plants of a particular climate.
The four domes which make up the humid tropic biome, with palm trees, a rubber plantation, teak, mahogany and a mangrove swamp, include species from the Amazon, Malaysia, Oceania and West Africa.
In four more domes, the warm temperate biome, are plants from the Mediterranean, California and southern Africa, including olives, orchids and citrus varieties.
World under glass
And between the two lies a garden open to the air, the cool temperate biome, with species from the UK, Japan, Chile and Australasia. There are plans to grow tea here for sale on the site.
The domes that make up the biomes are very light. The humid tropics biome weighs less than the air inside it. They are made of sections of tubular steel which form hexagons about 9m across, with the hollow frames of the domes filled with translucent, triple-layered ethylene tetrafluoroethylene (ETFE) foil.
This is a hundred times lighter than glass, and can be recycled at the end of the panels' projected 30-year lifespan. ETFE is anti-static and so self-cleaning.
Climate control is achieved partly through the ETFE panels' insulating properties, and by the use of a combined heat and power unit.
Breeding programme
The plants themselves also help to control the climate inside the domes, giving off more water and therefore cooling the air as it gets hotter.
Birds, insects and reptiles appropriate to the different biomes will live in the domes and will help to control pests.
The entire project is costing £74m ($110m). It also includes a small breeding programme for endangered conifers.
The Eden Project is working with a range of partners, including the International Institute for Environment and Development, the charity Plantlife, the Royal Botanic Gardens at Kew in London, and several university departments.
It opens on 17 March, when paying visitors will be admitted to the site near St Austell in central Cornwall.