in this interesting Iran Tour you can visit Shushtar Historical Hydrulic Sytem & Tchogha Zanbil. 

- Shushtar Historical Hydrulic Sytem: it demonstrates outstanding universal value as in its present form, it dates from the 3rd century CE, probably on older bases from the 5th century BCE. it is complate, with numerous functions, and large-scale, making it exceptional. The Shushtar system is a homogeneous hydraulic system, designed globally and completed in the 3rd century CE. it was registered by UNESCO site in 2009.

- Tchogha Zanbil: Ziggurasts were a form of ancient Mesopotamian mud-brick templetower common to the Sumerians, Babylonians and Assyrians from approximately 2200 until 500 BCE. Some of these architectural marvels still stand today. Iran, houses the world's oldest ziggurat, which was built in 2,900 BCE and is one of the four Elamite religious structures in Mesopotamia. The other three are Susa ziggurat (1,800 BCE), Haft Teppeh (1,375 BCE) and Choqa Znbil (1,250 BCE), all in Khuzestan Province. it was registered by UNESCO site in 1979.