Dujiangyan is an irrigation infra-structure built in 256 BC during the Warring States Period of China by the Kingdom of Qin. It is located in the Min River in Sichuan province, China, near the capital Chengdu. It is still in use today to irrigate over 5,300 square kilometers of land in the region. The Dujiangyan along with the Zhengguo Canal in Shaanxi Province and the Lingqu...