There is evidence for human inhabitance in this area in the 4-5th millennium BC. Qazvin was part of the Median territory, but the foundation of Qazvin city dates back to the Sassanid era as a military base.
Qazvin area was split from Zanjan province in 1994 and was annexed to Tehran province. Later in 1997, This was separated from Tehran and was introduced as a new province.
Qazvin province is surrounded by Gilan, Mazandaran, Alborz, Markazi, Hamadan, and Zanjan provinces. Alborz Mountains cover the north of the province, while the south is covered with Qazvin plain.
Altitude variations cause climate variation in different parts of this province. Cold mountainous weather in the north, Temperate weather in foothills, and semi-arid climate in the plains.
The best time to visit is spring and summer.