California architect Eugene Tsui first conceived of his 2,000-foot-tall tower for Oakland, but after officials balked at the idea--it would have dwarfed everything around it--he decided to bring it to Shenzhen, a booming port city in southern China.

The tower would be built on a man-made island in the bay, surrounded by mangrove swamps that would filter the polluted water, as windmills hummed on the edifice above. The tower would provide clean energy for the surrounding area, and its apex would contain restaurants and observation decks.

Tsui says that Chinese officials have previously failed to consider the environmental toll of Shenzhen's rapid growth, but notes that the tower would be an ecological symbol of a better future.