The Three Gorges Dam is the world's largest dam, heaviest man-made structure, world's largest concrete structure, and biggest electrical power plant, spanning the Yangtze River in Hubei province, China. At full capacity, it is expected to produce 22.5 gigawatts, enough to power almost 20 million homes. The Three Gorges Dam is the largest construction project in China since the Great Wall (completed in the late 15th century) and the Grand Canal (completed in the late 7th century). It cost 180 billion yuan (roughly $25 billion USD) to build, 25 billion yuan less than expected.

The Three Gorges Dam is 2,335 meters (7,661 ft) long, 185 meters tall (607 ft), and 115 meters (377.3 ft) wide. Construction on the Three Gorges Dam began in 1994 and the dam will be fully operational in 2011. The dam is expected to pay for itself through electricity generation by around 2020. With regular maintenance, the dam could stand for thousands of years, like the Grand Anicut in India, which was built approximately 2000 years ago. Truly a structure for the ages.

The primary function of the dam is to control flooding, with the generation of electricity as a secondary function. Every few decades, major flooding of the Yangtze occurs, killing thousands, displacing millions, and doing billions of dollars in property damage. Floods in China have a grim history: the flooding of the Yellow River in the summer of 1931 killed over 2 million people through drowning, disease, ensuing famines, and droughts, making it the deadliest natural disaster in human history. The Three Gorges Dam blocks the waters of the river and causes them to be released in a measured fashion, preventing flooding.

The reservoir created by the Three Gorges Dam will be over 660 km (410 mi) long and 1.12 km (0.70 mi) wide on average, containing 39,300,000,000 cubic meters (9.43 cu mi) of water, with a water level of 175 meters (574 ft). This will be the largest reservoir of any dam in the world. When at full capacity, the Three Gorges Dam will reduce coal consumption by 31 million tons per year, saving hundreds of thousands of lives affected by disease caused by smoke from coal plants. Advocates of the dam say this benefit, alongside the control of flooding, outweighs any negative environmental impact the dam may have.