The Allahverdi Khan Bridge popularly known as Si-o-se-pol, the bridge of thirty-three spans, 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. Hopefully one day, you'll be able to visit this interesting country?.