Qazvin in the ancient writings of Europe have been called old city "Arsas" or "Arsasia" and in the greek histories "Razhya" and in the era of Ashkanian on its founder "Ardepa".
Sasanian have called it " kashvin" , it means the land that shouldn’t be ignored, some people called it "Qasvin" or the city where people are strong and firm and some historians called it "kaspian".
According to historical documents, the age of Qazvin region related to Median era, ninth century BC. At that time, mountainous area of Qazvin south and south west was regarded as Median territory which was invaded by different nations, including Ashur and Kasiha nations.
Qazvin was recognized as Muslims border in the following of it's conquest in the year 21 Hq .There are the plenty of Hadiths that are narrated about Qazvin's virtues.
During the Safavid era and after war(Chaldoran) in the year 920H, Qazvin is considered morely and it became Safavid capital gradually and the collection of palaces and royal mansion were constructed on it. The other collections are smaller sample of historical buildings that have constructed in Esfahan where was the next capiltal of Safavid government..
Qazvin is considered as an important scientific center since third century (AH) and it had the great authors and scientists including: Ibn Majd, Najm Al-din Katebi, Imam Abolqasem Rafe'I Qazvin, Imam Ahmad Qazali, Zakariaye Qazvini, Hamdollah Mostoufi, Allame Ayatollah Rafi'i Qazvini, Obeid Zakani, Allameh Dehkhoda, Allameh Mohammad Qazvini and…..Qazvin's historical monuments including: Kolah farangi mansion and Sardar A'liqapu, Safavid buildings, Hamdollah Moustofi tomb, Shah Abbas bath, Qeisarie Bazaar, Hassan Sabbah castle on Alamut area, Sardar mosque-seminary, the great Jame mosque, Imamzade Hossein, Nabi mosque and Peiqambarie Seminary. Qazvin in addition to historical and agricultural records is regarded one of the industrial center in Iran where by having 1700 industrial branches and two industrial cities including Alborz"where is the first industrial city in Iran, founded in 1346" and " Lia" has a superior location in Iran's industry.
The customs of Qazvin's people
Yalda night (Chelle), Festival Pomegranate, Fandogh Festival ,Tiregan Festival, Norouz, Norouzi Khani, Sizdah bedar, Panjah bedar
Sweetmeats: Nan Chayi, Nan Qandi, Nan Nokhodi, three-colored Baqlqva
Fruits: Walnut, Pistachio, grapes, Pomegranate
Imamzades, mosques, churches, water reservoirs, edifices, house, gates, baths, Bazaars, castles, mausoleums
Peaks, caves, Barajin garden, Evan lake, Niyaq stony verandas, Yale Gonbad hot water, khareqan hot spring, Andaj rocks, Bashgol protected area