Before Islam came to Iran the major religion was Zoroastrianism, named in honor of its founder, Zoroaster, and arguably the world's first monotheistic religion. Zoroastrians held seven things to be sacred including the four elements of which fire was considered to be preeminent.
The main Zoroastrian festival was the New Year, Nowruz (literally new day) which took place as the sun entered the first point of Aries or 0 degrees ecliptic longitude on or about March 21st.
The festival of Nowruz has survived as the main festival to the present day, when families gathered together very much as Christmas in Christian societies.
Seven kilometers to the west of Isfahan there are remains of one of these places of worship, known as the Atashgah (or place of fire) seen here on top of a hill? The walls are made of mud brick with the layers separated by reads from one another. The whole is surmounted by a small circular building. It is worth climbing up to the top, although there is no clear path, as view from the top across the plain of Isfahan is unforgettable. The building was used by the Ismaili inhabitants of Isfahan to hide from tax collectors.
The fire temple is a big round fireplace with multiple valves. The building is made of mud bricks 40 cm and a diameter if 14 cm length. Large foundation started around the middle of the hill and above the sturdy pillars was made in the past as well as the rooms they had. There is a round building on the top and it has not made any taller building. It has 8 corners and in every corner has a window facing out. This fire temple has 7 large widows and an entrance that the fire was visible from all directions.