Eating locally is all the rage these days, especially for city dwellers looking to shrink their carbon footprint. But it's tough to do that in a city, as farmers need to drive their goods in from the country, and that takes energy.
The Plantagon is a design for an enormous urban greenhouse, placing a spiraling vertical farm in the heart of a city. Is this really feasible? I'm not sure, but if it is I would sure like to live near one.