Chehel Sotoun Mansion or Pavilion is one of the important monuments of Safavid period in Qazvin located in the center of Qazvin City, south of Sabzeh Meidan (Azadi Sqaure) in a large garden. It is the only kiosk left from the royal palace complexes of Shah Tahmasp period. This monument was refurbished by Mohammad Bagher Sa'ad Al-Saltaneh, the then governor of Qazvin, in Qajar period and named "Chehel Sotoun".
The murals of the first floor are a good example of Qazvin miniature and enjoy worldwide fame. The style of these murals has been inspired by political changes, in a way that the emergence of Nader Shah and Afsharid dynasty can be seen in Chehel Sotoun. Moreover, Qajar emergence can be seen in the third layer of the palace murals which have faded over time. This walls that are decorated with murals are unique, and the existence of three layers of murals demonstrate the passage of different historical periods.
Chehel Sotoun Mansion of Qazvin was registered in the list of Iran's historical monuments in 1956 under the registration number of 389.
This monument is currently being used as museum of calligraphy.