Band-e Kaisar

The Band-e Kaisar (lit. 'Caesar's dam'), Pol-e Kaisar ("Caesar's bridge"), Bridge of Valerian or Shadorvan was an ancient arch bridge in the city of Shushtar, Khuzestan province, Iran, and the first in the country to combine it with a dam. Built by the Sasanians during the 3rd century CE, using Roman prisoners of war as the workforce, it is the easternmost example of Roman bridge design and Roman dam. Its dual-purpose design exerted a profound influence on Iranian civil engineering and was instrumental in developing Sasanian water management techniques. The approximately 500m long overflow dam over the Karun, Iran's most effluent river, was the core structure of the Shushtar Historical Hydraulic System (‌) from which the city derived its agricultural productivity. The arched superstructure carried across the important road between Pasargadae and the Sasanian capital Ctesiphon. Repaired repeatedly throughout the Islamic era, the dam bridge remained in use until the late 19th century. In 2009, it was designated by UNESCO as Iran's 10th World Heritage Site.

Dam data from Wikidata (CC0) plus curated additions. Summary from Wikipedia (CC BY-SA).