Sadah Castle is an archaeological defensive fortification in the state of Sadah and the governorate of Dhofar, it has been built in the centre of the state, the date of its construction does not know, this is due that it had been built in the era of Al-Busaid, its reputation has emerged during the reign of Sultan Timur bin Faisal, where the region witnessed a recovery of the frankincense market in the second half of the nineteenth century until the middle of the twentieth century AD, Prior to this, the city was not populated, Given the frankincense trade flourished, it became a berth for ships, which are carrying frankincense from neighboring areas, as it was close to the valleys where Boswellia sacra trees grow, with natural stores to store the harvest of these trees, as well as their abundance of marine resources.
The Castle acquires its historical importance through its supervision of all the eastern regions from Bandar Sadah to Bandar Hasak, it served as the link among these areas and Salalah, the capital of Dhofar Governorate. It also supervised for regulating the social conditions, it managed the commercial situation over that side, and it was a center of state administration and the military garrison since the beginning of the twentieth century until 1982.
The building area occupied by the fortress is about 152 square meters and its height is about14 m. The fortress consists of three floors:
Ground Floor: it includes El-Vali/ Governor Council the "Al Barza", a weapons and ammunition storehouse and the "The punishment" prison.
The first floor: it contains three dorm rooms, including: two rooms for the governor and its family, guest rooms, a store for food, kitchen, water house and a rest between the rooms called Al-Mahdra.
The second floor: It contains a military wing and a tower to observe, what is happening in the city and a rest between the rooms.
The Castle contains holes at the top of its entrance, from which hot water and boiling oil were poured when exposed to attack, and holes in the outer wall to shoot fire. The Ministry of National Heritage and Culture renovated the fortress in 1991 on the same old style, and used local materials, and it furnished with antiques and traditional artifacts that the governorate of Dhofar is famous for. In addition to models from the governorates of Oman, in 1994, the Fortress was inaugurated for visitors.