This mosque is one of the oldest and nonpareil mosques in Iran in which orders of architecture along with the art of different periods are greatly noticeable.
Made in 807 A.D. by Harun-Al Rashid, the Aaron arch or the old cella is the oldest part of the mosque which is linked up with its east entrance vestibule. It is said that the foundation of the mosque is laid on a fire-temple. From four directions of a 4000m² yard there are four elevated verandas which a long portico is built on both sides of them.
Made by Amir Khomartash in the years between 1106 to 1115 A.D. the two-layered brick dome and the south nave contain five valuable plaster-work inscriptions in Sols, Nastaliq and Kufic calligraphy which are masterpieces of Iranian Art.