Archeological findings in the Qazvin plain reveal the existence of urban agricultural settlements as far back as 7000 BC.

The name “Qazvin” or “Kasbin” is derived from Cas, an ancient tribe that lived south of the Caspian Sea millennia ago.

Qazvin geographically connects Tehran, Isfahan, and the Persian Gulf to the Caspian seacoast and Asia Minor, hence its strategic location throughout the ages.

During the Qajar dynasty and contemporary period, Qazvin has always been one of the most important governmental centers due to its proximity to Tehran.

Qazvin is situated close to Alamut, where the famous Hasan-i Sabbah, founder of the secret Ismaili order of the Assassins, operated from.

Qazvin is where the coup d'état of General Reza Khan, with his Russian-trained Cossack brigade, was launched from – which led to the founding of the Pahlavi dynasty in 1921.

Among these is the current Mayor's office (former Ballet Hall), a water reservoir, and the Cantor church where a Russian pilot is buried.

According to explorers Pietro Della Valle, Jean Baptist Tavenier, Johannes Chardin, and others, there have been many Christians of various sects living in Qazvin for centuries.

Qazvin is the location of the Saint Hripsime church, and it is also where four Jewish prophets gave tidings of the arrival of Jesus Christ.

These are castles and fortifications left over mostly from the Isma'ili movement of the Middle Ages: Another grand attraction in Qazvin Province, is the tombs of two Saljuki era princes, Aboo Saeed Bijar son of Sad and Aboo Mansoor Iltai son of Takin, that are located in two separate towers known as the Kharaghan twin towers.

The agricultural produce of the land is grape, hazelnut, pistachio, almond, walnut, olive, apple, wheat, barley, sugar beet, pomegranate, fig, and cereals.

[citation needed] In recent decades, Qazvin has become a developing pole of the country, primarily due to its preferable location.