Niasar Fire Temple, called Chahar Tagh and located 28 kilometers west of Kashan city, is a structure with a dome, over a rock at the highest point of Niasar Village. The fire temple, which can be seen from quite a distance, has remained relatively intact since the time of Sassanid dynasty.
Archaeologists have revealed generally there would be a number of other premises around fire temples where Zoroastrian monks used to gather together for worship. Although it is not known whether this building was used for this purpose, there are rows of stones laid together near the fire temple which are remnants of a building belonging to the Sassanid era. Since the fire over the Niasar temple could be seen from distance, the building might have had a symbolic role.
The fire temple is a 14*14-meter building which contains a chamber. There are no walls on the four sides of the chamber. The fire temple has been made of stones bonded with mortar. The stones used in the lower part of the building are normal and those used in the arches and upper parts are square-shaped, looking like big bricks.
The lower parts of the building have been coated with plaster in recent years. All walls surrounding the fire temple have been decorated with stucco carvings. The main dome of the fire temple had previously collapsed and was reconstructed in lights of efforts of Colonel Bahonar from the Ministry of Culture and Art. However, it was modelled on Islamic domes while the original dome was egg-shaped, according to the famous French archeologist, Andre Godard.
There is an interesting point in the structure of the fire temple: some of the stones used in the building have older and different cut than others. These stones had been quarried from a cave down the temple for use in the construction of the fire temple. This reveals the fact that the Niasar cave is older than the fire temple.