The city, where the first settlements were 4000 years BC, but it became known in the time of Medes (400 BC). It was the capital of Persia during the reign of Hassan i-Sabbah (1090) and remained so until the invasion of Mongols. Then Shah Tahmasp (1524–1576) made Qazvin the capital of the Safavid Empire .
The fortress of Alamut is considered to be one of the most mysterious constructions in Iran. This fortress is located at the top of a narrow rock base approximately 180 m above ground level. It was built by Hasan i-Sabbah back in the 9th century as a castle. He was a conqueror and the fortress was a self-sustaining stronghold during major confrontations. At the invitation of Sabbah scientists, magicians and mystics were working here.
Alamut Gorge is also famous for its lake. Evan Lake (Ovan Lake) is a natural pearl of Alamut and Qazvin. Interestingly, this lake is fed not from the surrounding rivers, the only tributary that flows into the lake, is a stream with the same name, Ovan, coming down from northern mounts.
In Qazvin there is also a construction that is considered one of the most beautiful Qajar house named Aminiha. It was not owned by merchants and shahs, but commoners. The certain Islamic rituals were performed here.