The Shustar Historical Hydraulic System (Khuzestan Province, south-west of Iran) were established during the reign of Darius the Great, the Achaemenid king of the 5th Century BC. The system included in itself 10 water-mills: the world’s greatest industrial complex before the Industrial Revolution. Utilizing the available water resources by guiding them through a network of underground canals beneath the ancient city of Shushtar, which follows the climatic conditions prevailing throughout the region, the technique proves as a most thoughtful manifestation of urban-hydraulic architectural form.