Throughout the arid regions of Iran, agricultural and permanent settlements are supported by the ancient qanat system of tapping alluvial aquifers at the heads of valleys and conducting the water along underground tunnels by gravity, often over many kilometres. The eleven qanats representing this system include rest areas for workers, water reservoirs and watermills. The traditional communal management system still in place allows equitable and sustainable water sharing and distribution. The qanats provide exceptional testimony to cultural traditions and civilizations in desert areas with an arid climate. The Persian Qanat system is an outstanding example of a technological ensemble illustrating significant stages in the history of human occupation of arid and semi-arid regions. Based on complex calculations and exceptional architectural qualities, water was collected and transported by mere gravity over long distances and these transport systems were maintained over centuries and, at times, millennia. The qanat system enabled settlements and agriculture but also inspired the creation of a desert-specific style of architecture and landscape involving not only the qanats themselves, but their associated structures, such as water reservoirs, mills, irrigation systems, and gardens. There are qanats in many cities of iran, such as Isfahan, Arak, Kerman, Yazd, Southern and razavi Khorasan province.