Shahrestan Bridge (Esfahan)

 place with historical importance, interesting place, bridge

Shahrestan bridge near Isfahan is one of the oldest surviving bridges in Iran, built in the 14th Century (C.E.). It crosses the Zayandeh River at the village of Sharestan.
The construction clearly derives from Roman prototypes and the huge piers were designed to defend its pontoons from the torrent of the Zayandeh. The large prows are repeated on the down-stream side of the bridge where their object is to reduced the eddies which might otherwise erode the masonry.
Following the Roman model there are secondary water channels set into the piers. These expand with the curvature of the main arches and can therefore carry off a greater volume of water. Because of the risk of damage as high volumes of water poured through the narrower sections, additional venting channels run from the secondary channels back into the main channels, where, because of their greater width, the water level was likely to be less.