Built by Shah Abbas II on the foundations of an older bridge, the Khwaju bridge links the Khwaju quarter on the north bank with the Zoroastrian quarter across the Zayandah River. It also functions as a weir; the downstream side is formed as a series of steps carrying the water to a much lower level.
On the upper level of the bridge the main central aisle was utilized by horses and carts and the vaulted paths on either side by pedestrians. Octagonal pavilions in the center of the bridge on both the down and the upstream sides provide vantage points for the remarkable views. The lower level of the bridge may be accessed by pedestrians and remains a popular shady place for relaxing.
Sources:
Blair, Sheila S. and Jonathan M. Bloom. The Art and Architecture of Islam. New Haven: Yale University Press, 1994.
Michell, George. Architecture of the Islamic World. London: Thames and Hudson, 1978.
Pope, Arthur Upham, ed., and Phyllis Ackerman, assistant ed. A Survey of Persian Art from Prehistoric Times to the Present. Vol. 3, Architecture, Its Ornament, City Plans, Gardens. 3rd ed. Tehran: Soroush Press, 1977.