Chehel Sotoun is one of the most important monuments of Safavid era which is located at the center of a large garden. It is the only edifice left from the royal palaces of Shah Tahmasb times.
This octagonal monument with an area about 500m² is built on the basis of a Turk architect’s plan in two storeys, containing some small chambers and halls in each storey.
The murals of the first floor are a typical work of Qazvin Painting School which is famous worldwide.
The large hall of the upstairs with five-span sash windows in four directions connects with the ambulatory which is arcaded with a counter decorated roof.
The monument is now used as a calligraphy museum. It is said that the mansion of Hasht Behesht in Isfahan is made in imitation of this palace.

Chehel Sotoun Museum-Palace