The oldest monument from ancient times exists in Isfahan and it is a monument similar to a fire temple that is located on Isfahan Road to Najafabad near Menar Jonban on top of a rocky hil.
Most of Islamic historians such as Ibn Khordadbeh, Hamdollah Mostofi and Ibn Hawqal have referred to this monument and called it a fire temple. Foreign scientists as well have studied and investigated the fire temple and Maxime Siroux and Andre Godard from France are some of them.
The important feature of this monument is the bricks building the current ruined fire temple that few monuments have such bricks in terms of their size. According to experts, these bricks are made of mortar and mud with small pebbles. They used to also add the reeds around Zayandeh Rood to add to its stability.
The building of this monument is considered to be even before Sassanid era. Studies conducted by IZMEO announce that the building dates back to Elam Civilization. This is also in line with studies and investigations conducted on fire temples remaining from Sassanid era in Natanz, Kashan, Yazd, Azerbaijan and Nain because fire temples would not be built on top of mountains or hills at the time but in places more easily accessible. Therefore, it can be claimed with certainty that Isfahan Fire Temple is a sign of more amcient civilizations than Sassanid era and dynasties before it.