set behind fortified walls the buildings of the Topkapi Palace are an example of an architectural feature unique to Islam-an enclosed city within a city, called a citadel. the Alhambra, built in Granada by the rulers of the Nasrin dynasty in 1238-1358,is another well-preserved example of this feature.
the citadel in Aleppo, Syria, stands on a partly natural, partly man-made mound that dominates the city. the mound was fortified from ancient times, then the citadel was developed for military uses. Substantially rebuilt in the 12th century by Zangid rulers Imad al-Din Zangi and Nur al-Din, it was remade in the form in which it survives today by Ayyubid ruler al-Malik al-Zahir Ghazi in 1186-1216. he strengthened the walls, red the moat around the citadel, built the bridge across the moat and furnished the furnished the citadel with all the necessities of urban life, including granaries and cisterns.