The original small fort was built in c. 1710 by Omani Arabs, After the expulsion of the Portuguese from the East African coast in 1699. A wall of a Portuguese chapel, visible from the inside, was used as a prison and the quarters of the Sultan’s Baluchi bodyguards, when Sultan (Sayyid) Said moves his capital to Zanzibar (this was in 1822) he was accompanied by Baluchi soldiers who were sent to posts throughout East Africa to enforce the role of local Oman governors. Iron guns lined the seafront at Forodhani. The Soko Kuu (Big Market) was located outside its walls.
In the 20th Century, from 1905 to 1928, the Old Fort initially served as a terminal of the Zanzibar – Bububu Railway. In 1946, after railway had been removed, a new gatehouse was designed by the Government architect Ajit Singth, as the headquarters of the Ladies Club. A big door with a smaller inset door, from the house of a brother of Sultan Humoud b. Muhammad (1896-1902), was built into it.
In the 1990s, the gatehouse was restored, and an Amphitheatre was added with financial assistance from the European Union (EU). Excavations have revealed that the Old Fort might have been the site of a substantial Swahili town from the 11th Century, and part of the palace of the Shirazi Queen Fatuma (c. 1650-1715). The Old Fort is now used as a Cultural Centre and the headquarters of the Zanzibar International Film Festival (ZIFF).