China is building the world's largest hydroelectric dam in the densely populated and historically significant "Three Gorges" region. Problems abound. More than 30,000 hectares of farmland and 13 towns and 140 villages will be submerged and the lives of more than one million people will change irrevocably. Besides being one of the most challenging engineering projects ever, this undertaking will require one of the biggest resettlement efforts in recent history.