The Tarikhaneh Temple , also called the Tarikhaneh Mosque , is a Sassanid-era monument located on the southern limit of the present day city of Damghan, Iran. This structure was initially used as a Zoroastrian Fire Temple during the Sassanid period, however, after the fall of the Sassanid Empire it was rebuilt and converted into a mosque in the 8th century. The monument is, thus, known as the oldest mosque in Iran