Shushtar Hydraulic System

Shushtar, a town on the Karun river in Khuzestan, is built around one of the most ambitious water systems of the ancient world. UNESCO inscribed the Shushtar Historical Hydraulic System in 2009, and its origins are generally traced to the Sasanian period, perhaps with earlier Achaemenid foundations. Its purpose was to raise and divide the river so that its water could irrigate the surrounding plain and drive mills.

The system combines weirs, bridges, tunnels and canals. The Band-e Kaisar, or Caesar's dam, a long bridge-weir across the Karun, is traditionally said to have been built by Roman prisoners taken after the emperor Valerian was captured by the Sasanian king Shapur I in 260. The Gargar canal, cut from the river, carries water past the town and into the countryside.

The most dramatic sight is the mill complex at the edge of the town. Here water is led through tunnels cut into the cliff and released in falls and cascades down the rock face, where it once turned the wheels of dozens of mills. Visitors walk on bridges and terraces among the old mill chambers, with the sound of falling water all around them, while below, the channels join again and run on towards the plain.