The largest underground city in Iran is the city of Ouyi in Nooshabad, Kashan. This famous city is one of the most astonishing underground cities in the world whose fascinating architecture catches the viewers' eyes. The history of this city dates back to the Sassanid period about 1500 years ago. This underground city was discovered accidentally by a man digging a well in his house in 2006. The first floor consists of several corridors to mislead enemies. The second and third floors were used as shelters during wartime. This underground city will surely mesmerize you by its winding corridors, chambers and unique architecture which make it an obligation during your stay in Iran.