The city of Noush Abad is a memorial from the Sassanid era dating back to 1500 years ago, which is named after the Sasanian Anoushirvan. The city was a home between Rey and Isfahan, which was of great commercial importance due to its proximity to the Silk Road, and has been infinitely infuriated by bandits, Mongols, Afghans.    To defend the city, the construction of a secret city and underground as a refuge came to the minds of city’s people. Undergroundcity has an area of about 4 square kilometers and is located in three levels from 4 meters to 23 meters underground from a series of wells, the corridors and rooms are made of clay and no stone or brick is not used in this structure. The air conditioning system is quite natural and, according to Pascal’s law, the pressure difference and air flow are U-shaped. The brightness of this underground city is achieved through light bulbs that are made from animal fat.