【正确答案】Dujiangyan is located on the Minjiang River in the western part of the Chengdu Plain, about 50 kilometers from Chengdu. Its construction began in the third century BC. What characterizes it most is that it can regulate the flow of water without a dam. For more than 2, 000 years, Dujiangyan has effectively served the purposes of flood prevention and irrigation, making the Chengdu Plain a fertile land that ensures stable yields despite drought or excessive rain and one of the major grain-producing areas in China. This project embodies the wisdom of the Chinese people to coexist in harmony with nature and is the oldest water conservancy project in the world that is still in use and controls water without a dam.