Known as the oldest Jameh Mosque in Iran, Jameh Mosque of Qazvin was built in 807 AD. Like many other mosques in the country, the mosque was built to replace a Zoroastrian fire temple which dated back to the Sassanian Empire (224–651 AD). The mosque was relatively small in size until the Safavid Dynasty (1501–1736) when numerous additions were made to the mosque which resulted in the expansion of mosque. In fact, most of what has remained today and the architecture style you see in the mosque is from the Seljuk (1037–1194) and Safavid eras.
Jameh Mosque of Qazvin has several sections, there are multiple inscriptions in the mosque as well as two museums, one dedicated to stone-works and pottery and the other one showcases antique doors and windows. There is also a water reservoir (Āb anbār) inside the mosque which was built during the Safavid Dynasty. As the water reservoir is not active anymore, visitors are allowed to enter the huge storage room. Parts of the mosque have also turned into public library.
Despite all the incidents, disasters, and attacks, the mosque still stands strong. The mosque was heavily damaged by the Mongols invasion and Afghans attacks and was put to fire several times throughout the history, despite that, it still has a lot to offer to visitors.