China already has the world’s largest population (1.3 billion), the world’s most polluted cities (pollution-related ailments are the leading cause of death), and plans to build some of the world's tallest structures (the Shanghai World Financial Center is still under construction) to rival the current record holder, Taipei 101. This weekend, China will come one step closer to obtaining its next superlative when the last structural concrete is poured for the Three Gorges Dam.  When it comes online fully in 2009, it will be the largest hydroelectric dam in the world.

Although the officially reported budget for the dam is $25 billion, estimates of the actual cost are as high as $100 billion, which would also make it one of the world’s most expensive construction projects. Plus, the $100 billion does not factor in the dam's secondary costs, which include relocation expenses for the million people displaced by flooding, the loss of fertile land, bribes and corruption, and extensive environmental damage. The most environmentally destructive human construction, perhaps? That’s a record no one’s in any rush to publicize.

Google Earth's coverage of the region is disappointingly low-res, but as it always does, NASA’s Web site comes through with a giant satellite photo of the region. —John Mahoney

Related: "How High Will They Build?"