The Shushtar Historical Hydraulic System, located in Iran's Khuzestan province, is an ancient Sasanian-era irrigation system that includes 13 dams, bridges, and canals. This complex engineering feat was designed to divert the Karun River to irrigate agricultural lands and supply water to the city. The system is renowned for its sophisticated design, which includes tunnels and watermills, and is considered a unique and impressive example of ancient water management.