Zoroastrian tradition recognizes a hierarchy of consecrated fire, and a fire temple's status and name follow directly from which grade of fire it houses, with the highest grade, an Atash Bahram, requiring an elaborate consecration process that in traditional practice gathers and purifies fire drawn from a substantial number of distinct sources, including fire associated with different trades and even, in the fullest traditional accounts, fire produced by lightning, before the composite flame is installed with an extended ceremony that can take well over a year to complete.
Fire temples of lower grade, an Atash Adaran serving a town or community and an Atash Dadgah maintained even in more modest or domestic settings, follow simpler consecration procedures appropriate to their more local scope, and a community's access to the highest grade of fire has historically depended on the resources and organization available to sustain the demanding consecration process. Only nine Atash Bahram fires are maintained today, eight of them in India among the Parsi community and one in Iran, reflecting how few communities historically possessed the resources to found and, crucially, to sustain such a fire across generations without interruption. The architecture of the temple itself is generally understated on the exterior, giving little external indication of the fire's grade or the building's significance, with the sanctity concentrated entirely in the inner sanctum and its carefully maintained flame rather than expressed through an imposing facade.