Shushtar Historical Hydraulic System , is an island city from the Sassanid era with a complex irrigation system . Located in Iran's Khuzestan Province . It was registered on UNESCO's list of World Heritage Sites in 2009 and is Iran's 10th cultural heritage site to be registered on the United Nations' list .
Shushtar infrastructure included water mills , dams , tunnels , and canals . GarGar weir was built on the watermills and waterfalls . Bolayti canal is situated on the eastern side of the water mills and water falls and the functions to supply water from behind the GarGar bridge to the east side of water mills and the channel the water of river in order to prevent the damage to the water mills . Dahaneye shahr tunnel (city orifice) is one of the three main tunnels which channeled the water from behind the GarGar weir into the water mill and then run several water mills . Seh koreh canal channels the water from behind the GarGar bridge into the western side . In water mills and water falls , there are noticeable mills we can see a perfect model of haltering to run mills .
The Band-e Kaisar ("Caesar's dam") , an approximately 500-metre (1,600 ft) long Roman weir across the Karun , was the key structure of the complex which , along with the Band-i-Mizan , retained and diverted river water into the irrigation canals in the area . Built by a Roman workforce in the 3rd century AD on Sassanid order , it was the most eastern Roman bridge and Roman dam and the first structure in Iran to combine a bridge with a dam .
Parts of the irrigation system are said to originally date to the time of Darius the Great , an Achaemenian king of Iran . It partly consists of a pair of primary diversion canals in the Karun river , one of which is still in use today . It delivers water to the Shushtar city via a route of supplying tunnels . The area includes Selastel Castel , which is the axis for operation of the hydraulic system . It also consists of a tower for water level measurement , along with bridges , dams , mills , and basins .
Then it enters the plain south from the city , where its impact includes enabling the possibility of farming over the area called Mianâb and planting orchards . In fact the whole area between the two diversion canals (Shutayt and Gargar) on Karun river is called Mianâb , an island having the Shushtar city at its northern end .
The site has been referred to as "a masterpiece of creative genius" by UNESCO .