Anyhow, we'll never know/see the true artistic design and engineering of many pre-Islamic sites in Iran, because firstly Alexander destroyed most of Persepolis, and then the Moslem-Arabs, Mongols and Turks did the rest, instead replacing them with mosques & Islamic shrines. In the past 32 yrs, Mullahs regime has continued to destroy pre-Islamic buildings, monuments, etc.. in Iran, only to expand their Islamic this & that to glorify Islam.
Here is a bit about the pictures below:
Chahar-Taqi Fire Temple Design
Together with the Parthian era fire-temple / fire-house (atash-gah), the Ani fire-house is an early example of the fire temple design that came to be known in Iran as chahar-taqi meaning four directions. The walls and openings faced the four cardinal directions. The alignment of the walls or pillars of the fire-houses with the solar-based cardinal points has led some to believe that the fore-houses/temples served an additional function - that of using the position of the sun at sunrise, noon-meridian and sunset to determine seasons and significant days of the year. Zoroastrians mark these days with festivals, jashnes or jashans, and they were particular important for farmers in determining sowing times and for live-stock owners as well. The chahar-taqi design continued to be used for fire temples during the Sassanian era, that is up to 650 ACE. -- more here
Bazeh Khur Fire Temple, Khorasan, Iran - one of the oldest Chahar-Taqi temples dating to the Parthian era 247 BC - 224 AD
Sassanid ((226-651 AD) Chahar-Taqi (meaning four directions fire temple) at Niasar near Kashan, Esfahan (Isfahan) – Iran
Frankly, I see the very basic design & concept shared between above pics and Taj Mahal (the main temple and its adjoining structure). Taj Mahal was built in the 1600s? - can't find a photo of a Hindu temple predating Taj Mahal, which also would suggest providing the blueprint, so to speak, later for Taj Mahal.