The largest series of botanical landscapes in the world is being built in the Saudi capital, Riyadh.
The project recreates a history of plants in the last 400 million years
The gardens - covering 160 hectares (395 acres) - aims to re-create the 400 million-year-old history of the Earth's plants, trees and flowers.
The £100m ($200m) project is due to be completed in 2010.
The complex of gardens - to be called the King Abdullah International Gardens - is a gift from the city of Riyadh to the Saudi monarch.
The landscapes will be five times larger than the similar Eden Project in south-west England.
Built just outside Riyadh, the gardens will include four types of gardens - scientific gardens; water gardens; international gardens, sponsored by individuals and foreign embassies; and paleo-botanic gardens, which recreate the history of plants.
THE PALEOBOTANIC GARDENS
Devonian - 400 million years ago - multi cellular plants, like mosses and liverworts
Carboniferous - 300 million years ago - swamps and peat-filled wetlands
Jurassic - 206 to 142 million years ago - lush woodlands
Cretaceous - 142 to 65 million years ago - flowering plants
Cenozoic - 65 million years ago - vast variety, evolving with pollinators
Nick Sweet of Barton Willmore, a British company designing the project, says it will be like "Jurassic Park without the dinosaurs".
"There was a danger of the project being pompous about the scientific aspect", he told the BBC.
"People should respond like they would for example in London, taking their family to the Kew Botanical Gardens, throwing a Frisbee around."
The project is taking shape in the middle of an arid landscape, but three million years ago the same place was totally different.
The land which is known as Saudi Arabia today was back then covered with forests.
"It contrasts the desert environment of today with the green, verdant and lush place of three million years ago," Paul Kenrick, paleo-botanist at the Natural History Museum and scientific advisor to the project told the BBC.
"It illustrates how climate change can affect plant development."
The final garden of this section, called The Garden of Choices, will attempt to warn of what may happen to the Earth in the future as a result of different possible scenarios resulting from human activity.
Environmental concerns have not been overlooked. Sources of renewable energy will keep the gardens cool in the 45 - 50C temperatures of the desert.
Evaporation from the site will be kept to a minimum, with water being recycled wherever possible, designers said.