Friday Mosque of Qazvin: The Kabir Friday Mosque of Qazvin is among the oldest mosques of Iran. It is in Dabaghan Neighorhood on the west line of present Sepah Street. Different architectural styles from different periods are visible in the mosque. Maqsoreh-ye Kohan (old prayer niche), or Taq-e Haruni (arch of Harun), is the oldest part of the building. It is connected to the entrance vestibule and was built by Harun A-Rashid in 192 AH.

The foundation of the Mosque is based on an ancient fire-temple. The Mosque has eight big prayer halls on the four wings of the courtyard and an underground hall in the northwestern side finished by Sa’d-os Saltaneh in Qajar era. The mosque had many entrances in the seventh century AH, of which only two wntrances on the east and on the northwest of the mosque have survived.

The main entrance is on the east. This is located in Sepah Street and has a glorious portal with unknown founder. Haj Mahdi Qazvini reconstructed the portal and the vestibule after it had been destroyed. The courtyard has a rectangular plan stretching in an east-west direction. It covers more than 4000 square meters. The Mosque has four lofty porticos. There is a big pool in the middle of the yard filled by a canal coming from Sepah Street.

There is a drinking fountain between the pool and the eastern portico. A 10-step staircase connects it to the Khamartash Aqueduct. Water of the aqueduct passed through the fountain towards the southern part of the city. The northern portico and two grand minarets on the sides are decorated with colorful tiles.

It might reasonably belong to the King Tahmaseb’s time. Since the tiles of the minarets and porticos had been damaged over time, Sa’d-os Saltaneh, Qazvin governor, repaired the tile-works of minarets, portico and the dome by order of Mirza Ali Akbar Khan Atabak. The minarets can move like those of Isfahan. The western portico, facing the eastern one, belongs to the Safavid era and had been decorated with tiles.

some the contents were taken from wikipedia by tours of iran team.