Three Gorges Dam
The dam cost $180 billion Chinese Yuan Renminbi (about $30 billion USD). While this cost seems huge, it actually was $20 billion yuan (about $3.3 billion USD) less than the original budget of $203.9 billion yuan (about $34 billion USD). However, this cost will be recovered when the dam makes money by making electricity. In about 10 years, the complete cost of the dam will be recovered.