Smit and Ball set to work promoting the Eden idea jointly, though they were later to fall out. Legal recriminations continue today as Ball, now disconnected from the project, claims compensation. But the other alliance Ball set up- Smit with Grimshaw - flourished. Grimshaw's team included his ambitious young colleague Andrew Whalley and the brilliant veteran structural engineer, Tony Hunt. All three had worked together on the Waterloo project, and they immediately saw fascinating possibilities. Which was just as well, since they were all, along with landscape architect Dominic Cole of Land Use Consultants, to work without pay for some considerable time. Everybody - including, amazingly, even the lawyers who drew up the charitable trust that was to run Eden- was told the same.

When Grimshaw entered the frame in 1995, the only public money earmarked for Eden was a £25,000 pump-priming grant from the local authority, Restormel District Council, though Smit’s Heligan and Jonathan Ball also invested in the dream. Smit and Ball told Grimshaw that he had the opportunity to design the Eight Wonder of the World - and there was no money -yet - to pay him to do it. This is not the way the highly-successful Grimshaw, with an office of 120 people to feed, usually does business. But on this occasion, he did. Which immediately gave the project credibility. Which made it easier to raise money. And which would, eventually, attract the eye of the Millennium Commission.

Grimshaw is a soft-spoken, reticent man with owlish spectacles who has, bit by bit, made his practice into a world leader in advanced buildings. He knew he was onto a winner, he says, when he was down in Cornwall looking for a site for this new earthly paradise. He and Smit had rejected lots of other possible places because they were still surrounded by dusty industry - and the last thing they wanted was a Paradise covered in what looked like cement dust, with trucks rumbling past. But the Bodelva quarry, set in unspoiled countryside, was different. "It was isolated. It really was like a lost world. Being on top of a hill, you couldn't see it. It had undergrowth all round it. So you pushed your way through this undergrowth, and there was this absolute vision of a huge hollow. It was lost, unknown territory. That was a very inspirational moment. I felt we could do wonderful things there, from day one."

There was vegetation sprouting out of the cliffs, water trickling. "On the very first day, the idea of using the cliff, leaning against it, was there. The first time I saw it. By having a wall of green, with the building leaning against it, you almost double the size of the space. There's something about an ordinary greenhouse, where you look across it and see the glass on the other side. It takes away the feeling of being in the jungle. Whereas if you're looking at a rockface covered with greenery, you can really feel you're there."