By Mr.Ashayeri (JSI2361)

The Allahverdi Khan Bridge , popularly known as Si-o-se-pol (Persian: سی‌وسه‌پل, lit. '[the] bridge of thirty-three is the largest of the eleven historical bridges on the Zayanderud, the largest river of the Iranian Plateau, in Isfahan, Iran.
The bridge was built in the early 17th century to serve as both a bridge and a dam.It is a popular recreational gathering place, and is one of the most famous examples of Iran’s Safavid architecture.