Shushtar Historical Hydraulic System is an engineering masterpiece consisting of waterfalls, bridges, mills, canals and giant tunnels which work together in a systematic way, amazing to visit in your Iran trip. The primary construction of the system was established during Achaemenid era and developed in Sasanid dynasty. A branch of Karoun River had been taken to fill the moats around the city so that no enemies could enter the city. In constructing the 5-hectare-area structure, there has been a system designed to redirect the qanat water to the houses, mills and buildings. Visiting Shushtar Historical Hydraulic System is the reason for many engineers to travel to Iran!