Nizwa Fort was built during the reign of Imam Sultan bin Saif bin Malik Al Yarubi (1649-1679 AD) at the beginning of the eleventh century AH / mid seventeenth century AD. Building the fort took twelve years. Its height is 34 m, and its diameter is 45 m. It serves as a flat-roof platform erected on a base of crushed stones, its height is 15 m and it around 30 m to the ground. It is equipped with cannon holes. The entrance of the fort has a narrow staircase in the form of the letter ح (ح is an Arabic letter equivalent to H in English). It has seven doors, and at each door a turn. These doors have defensive openings at the top.