Bahla Fort The Bahla Fort is a World Heritage Site recognized by UNESCO. It was inscribed in 1987 and was given criteria iv. There are four significant fortresses in Oman and Bahla Fort is one of them. The other three forts are the Izki Fort, Rustaq Fort and as mentioned already, the Nizwa Fort. The Bahla Fort was erected sometime in the 13th – 14th century and it is on Jebel Akhdar, or the Green Mountain of Oman, which is also another famous landmark.