A Masterpiece of Creative Genius

Band-e-Kaisar
The Band-e Kaisar, also known as the Bridge of Valerian was a Roman stone arch bridge built in Shushtar, Iran. Around 260-270 CE when it was built, the bridge was combined with a dam – making Band-e Kaisar the first of its kind in Persia. The bridge-cum-dam is deep inside Persian territory, easily the eastern most Roman structure built during that time.
Shapur I, a Sassanid dynast then ruled Persia. The Sassanid era is considered to be one of the most important and influential historical periods in Persia. In many ways, the Sassanid period saw the culmination of Persian civilization, and constituted the last great Empire before the Muslim conquest and adoption of Islam.
According to Persian history, Band-e Kaisar was named after the Roman Emperor Valerian, who was captured with his entire army by the Sassanid ruler Shapur I. The dam bridge was used until the late 19th century and today Band-e Kaisar is part of a larger UNESCO World Heritage Site in the area.
The bridge is not in use today.
The Bridge
Band-e Kaisar, or Pol-e Kaisar translates to “Caesar’s bridge”, Kaisar being the Persian equivalent of Caesar. The word Kaiser in German and Czar in Russian have all been derived from the Roman word Caesar. It is also referred as Bridge of Valerian or Shadirwan. 
Valerian(253CE-260CE) was captured by Shapur I with his entire army after having been defeated in the Battle of Edessa (260CE). His vast labour force, which may have numbered up to 70,000 men including the Roman engineering corps, was employed by the victors for construction work in Shushtar, an important agricultural centre in south-western Iran.
Nothing is known about the agreement between the victor and the vanquished on the construction of the bridge but Shapur I must have been a wise and far- sighted king, because he exploited the Roman manpower, their designing and engineering skills and their adversity to build an asset that was to provide both connectivity and irrigation on a mammoth scale. What Roman got as the quid pro quo, is not recorded. Possibly an honourable release after they had built the bridge.
The Roman were given a free hand to design and construct the bridge. To service its large stretches of arable land, altogether some 150,000 hectares- the main purpose for constructing the dam-cum-bridge – the Romans set out to construct three structures: a canal called Ab-i Gargar, and the two dams of Band-e Kaisar and Band-e Mizan, which directed the water flow of the Karun river into the artificial watercourse.
Its dual-purpose design exerted a profound influence on Iranian civil engineering and was instrumental in developing Sassanid water management techniques.
The bridge was built on the most effluent river of Iran-Karun. The approximately 500 m long overflow dam, 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 Sassanid capital Ctesiphon.
History
There may be some exaggeration in the story related to its construction which came later through Muslim historians Tabari and Masudi in the 9th and 10th centuries. However, modern local names, such as “Roumischgan” for a nearby village, and a ‘Lurs’ tribe by the name of “Rumian”, give credence to this possibility. Moreover, local tradition ascribes to Roman settlers the origin of a number of trades, like the production of brocade, and several popular customs, corroborating the presence of Romans in that area in a large number and for a considerable period of time.
This new experiment, the first one in Persia of integrating bridge superstructure into dam design became a standard practice of Persian hydraulic engineering system, which lasted until about 1000 AD, when it culminated in the still existing Band-e Amir at Shiraz.
Construction
Some description of the engineering aspect of this bridge may be in order. Shushtar lies on a rocky plateau above the river Karun. The irrigation scheme put into effect after the arrival of the Roman labour force included three steps: First, the river was redirected towards the Ab-i Gargar, a channel which branches off the Karun at a point upstream of the dam construction site, second, re-joining the main river some 50 km south and in the process creating an island, called Mianâb (“Paradise”); and lastly, laying the bridge across the dried-up riverbed, with its foundations following a winding course in search for solid strata of sandstone. As the water flowed permanently over the top, the hydraulic structure conforms to the definition of a weir rather than a dam. but was most likely in the order of 3–4 meters, which was enough to supply water for the irrigation conduits on both banks during the dry season. Despite its modest height, the weir wall was quite thick (9–10 m) to accommodate the arcaded superstructure.
On top of the weir, a roadway supported by originally at least forty arches ran along its entire length of around 500 meters. The typical clear span of the Band-e Kaisar was between 6.6 and 9 meters.
The piers, protected on their upstream side by pointed cutwaters, were of rectangular shape and pierced by high-set flood ways; their considerable thickness of 5 to 6.4 meters each restricted the waterway by nearly one-half.
The piers and the foundation, on the outside, consisted of cut sandstone blocks bonded by mortar and joined by iron clamps; while the core was filled with Roman concrete, a building technique also observed in the Pa-i-pol bridge.
Finally, another smaller barrage, the Band-e Mizan, whose construction may postdate the Roman works, was erected upstream to control the flow of water into the Ab-i Gargar canal.
No one is sure how long it took to complete the bridge? Estimates vary from three to seven years.
The site has been referred to as “a masterpiece of creative genius” by UNESCO, a description that does only a partial justice to the grandeur and magnificence of this living monument of human creativity, skill and spirit.