While perhaps not as architecturally ambitious as the Dragonfly concept we looked at last week, this urban farming design from Swedish-American company Plantagon has the same environmentally-friendly ambitions along with a distinctly eye-catching design of its own.

Basically a giant spherical greenhouse, the Plantagon design is more squarely oriented towards food production and omits many of the more lavish interiors of The Dragonfly.

Plantagon explains the self-sustainable goals of the concept: "[The] greenhouse will dramatically change the way we produce organic and functional food. It allows us to produce ecological with clean air and water inside urban environments, even major cities, cutting costs and environmental damage by eliminating transportation and deliver directly to consumers. This is due to the efficiency and productivity of the Plantagon greenhouse which makes it economically possible to finance each greenhouse from its own sales."

Like the Dragonfly, the dramatic design isn't simply for show. The spiral ramp on the inside is intended to optimize growing conditions by controlling the angle at which the sun penetrates during summer and winter months through the glass exterior.

Hans Hassle, founder and CEO of Plantagon, argues that 80% of people on earth will live in urban centers by 2050, but plans for development of this greenhouse are far more advanced than this might suggest. The company believes that if everything goes smoothly it could have such a structure up and running in a major city within three years.

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