The largest stone complex of Iran belongs to Achaemenid Empire which is located in Fars province. It was registered in list of World Heritage in 1979.
Chogha Zanbil is an ancient Elamite complex in the Khuzestan province. It is the earliest Iranian building registered in UNESCO.
Historic Iran era dates back to 2500 years ago i.e. the time of the Achaemenid dynasty followed by Seleucid, Parthian, and Sassanid dynasties.