Sab Castle is the most intact castle remained from Islamic period of Sistan and Baluchistan Province. This monument that goes back to Safavid era and after that is among 27 historical monuments of the province that are still intact. This castle was built in Century 12 AH. The base of the original castle is a 36 25-meter rectangle built in two floors. As the height of the castle increases, its volume decreases and it appears as a "step pyramid" that leads to the monument's stability and keeping thick and high walls of the monument from landslide. In order to build Sab Castle, local skilled architects took advantage of their experience and mixed the seeds of a native plant with mud and made a type of sticky mortar. When dry, this mortar would not be washed away by the most severe showers and seasonal rains of Baluchistan. That is why the castle has remained stable and intact.
Sab Castle was registered in the list of Iran's National Heritage in September-October, 1996 under the registration number of 1715.