The Pol-e Khaju bridge, Esfahan. Contructed by Shah Abbas II from about 1650 both as a bridge and a weir. Resting on twenty four piers, it is divided by narrow channels of rushing water (in spring), each division covered with a pointed arch, above which an arcade of smaller arches run the length of the bridge. Sluice gates block the channels of water when it is required up stream. Hexagonal pavilions in the centre and at either end of the bridge add architectural significance and provide viewpoints. Steps on the downstream side provide access for washing.