An Atash Behram is the highest grade of fire in a Zoroastrian fire temple, symbolizing reverence and dignity. The process involves gathering and purifying 16 different types of fire, including lightning fire and fire from various professions. The sacred fire is continuously kindled as a focus of worship to Ahura Mazda. The purification and consecration ceremonies involve prayers recited over the 16 fires for specific numbers of days based on the source and type of fire. The final ceremony combines the fires into one Atash Behram fire, which is then enshrined in a temple room. Several Atash Behrams exist worldwide, each established at different times.
https://en.wikipedia.org/wiki/Atash_Behram