Najm Castle or (Qal’at Najm) located in Manbij city 118 km east of Aleppo Governorate and is about 377 meters above sea level. It was built on a high rocky plateau on the right bank of the Euphrates River, which gives it its geographical importance. The son of one of the princes in the time of the Abbasid Caliph Al-Mamoun in the ninth century AD, and during the era of the Byzantine Romans, the castle was named Caeciliana, which means the castle of the corridor, and it was also called ‘Manbij Bridge’ area. The castle consists of 3 floors, which is the basement or the foyer and contains granaries, water warehouses and secret outlets leading outside the castle, the first floor contains the rooms, the Prince palace, the bathroom, the long street and the horse stables. As for the third floor, there is the mosque and a distinctive building and stables for horses.