The inquiry into whether Mid Devon should get its own Eden Project starts today.
The original Eden in Cornwall is one of the most popular tourist attractions in the country and a major science centre.
But founder Sir Tim Smit says the area around Tiverton and Cullompton is an even better location. He claims it's the natural capital for agriculture - and his plans could make it the most important structure to be built in the country for the next thirty years.
If it goes ahead, just off junction 27 of the M5, it will be called Eden Westwood. It will celebrate food and farming, will have a designer shopping outlet and a surfing lake.
But it's controversial. Exeter MP Ben Bradshaw has campaigned against it - and some civic leaders in Exeter are concerned it may attract spending away from the city.