Chogha Zanbil is a ziggurat dedicated to Inshushinak, the Elamite god. Ziggurat is a kind of stepped pyramid that its origin goes back to religion and the place of gods among human in Mesopotamia and areas around it like southwest of Iran.
Chogha Zanbil Ziggurat is one of the major archaeological sites in Iran that was created by the Elamite king Untash-Napirsha as a religious building around 13th century BC. According to the inscriptions on the exterior of Chogha Zanbil bricks, the whole construct was dedicated to Inshushinak, the lord of Elamite and Susa.
The ziggurat has a 100 * 100 m (330*330 ft.) base that serves as both a temple and a tomb.
It consists of five separately built concentric levels with varying elevation and each level was constructed directly from the ground.
This form of architecture (each level built from the ground and not over the previous layer) is what differentiates Chogha Zanbil and Mesopotamia ziggurats.
The top of temple was where the most important cultic rituals were performed. There were four gates with the southwestern gate being the main one. It was named imperial gate by Professor Roman Ghirshman (French archaeologist) which was connected to the top by side stairs. Only King and first-rate clergies were allowed to walk in these stairs. On both sides of the entrance gate, the statues of guardian bulls and winged griffins glazed in terracotta were placed.
The monument was constructed using firebricks for the casing of structure and sun-dried bricks as filler. In the past, the exterior of the monument was decorated with blue and green glazed firebricks, inlaid ivory mosaics as well as opaque glass mosaics depicting prancing creatures.
Around the main ziggurat were other small shrines that were dedicated to other Elamite gods, the holy city was also protected by three layers of defensing walls.
Today, Chogha Zanbil lies approximately 40 km southeast of Susa and Khuzestan province. In 1979, UNESCO registered it as the first world heritage of Iran.