Qazvin located 150 km northwest of Tehran at an altitude of almost 1800 m, has been mentioned in the historical writings of ancient Greek. It is believed that the present city was founded by Shapur II of the Sassanid dynasty in 250 CE. Modern historians believe the name "Qazvin" is the Arabized form of "Caspian", in fact in old Ottoman texts the Caspian Sea was mentioned as "Bahr-el-Qazvin". Alamut Castle on top of Alamut mountain to the northeast of Qazvin, served as a sanctuary for the Ismailite assassins until it was conquered by the Mongol Hulagu Khan. Qazvin became the capital of Iran during the reign of Shah Tahmasp (1524-1576) of the Safavid dynasty.


Qazvin has long been known for its painting, calligraphy, stained glasses, illumination, woodcarving, and musicians. In 1967 an industrial city was founded on 900 hectares of land 15 km southeast of Qazvin. This city known as Alborz Industrial city, now includes around 450 industrial units and more than 1000 workshops and other organizations providing various services to the community. Since then Qazvin has become a major industrial center in Iran. The 2000 MW Shahid Rajai power plant on Tehran-Qazvin freeway is responsible for 8 percent of the total electricity produced in Iran.


Qazvin has several institutes of higher education. Imam Khomeini International University has been working as an international institute of higher education since 1991. At present 6300 Iranian students and 530 non-Iranian students are working towards undergraduate and graduate degrees. In 2011 this university agreed to allocate 50 hectares of its lands in Imam Khomeini Science and Technology Park of Qazvin Province (expandable to 100 hectares) to the construction of the Iranian Light Source Facility. The construction of this 3rd generation synchrotron will be of great benefit for science and technology in Qazvin, bringing Qazvin's industry and science into contact with the latest advances made possible by the ability to peer into the world of small scales.

The pavilion and the Ali-Qapu are the only buildings that survive from the Safavid Royal palace. They were repaired during the Qajar period and renamed Chehel-Sutoon (40 columns). The building is in the shape of an octagon. At present, it houses the Caligraphy Museum of Qazvin.

The Aminis' house in Qazvin dedicated to the memory of Imam Hussein, has some of the best examples of stained glass painting used to ornament carved wooden doors.

Shahid Rajai's power plant can produce up to 2040 MW of electricity. The power plant entered the national grid in 1992 and reached full capacity in 2001.