Hasan Abad Castle belongs to Ashkanid and Sasanid eras and it is located five kilometers from Sanandaj, in the south of a village of the same name. This mountainous castle has tall stone walls and towers along the walls. The main official and martial buildings are constructed inside the castle at the highest point of the mountain at a height of 400 meters and are mostly of brick architecture. From the lowest part of the wall to the highest point of the mountain, some platforms are constructed as floors for the construction of building for inhabitants of the castle. Hasan Abad Castle has been registered as a national monument of Iran.