Dar Essoultane is located in the high casbah, at the level of Bab el Djedid. Started in 1516 by order of Aroudj Barbarossa and enlarged by Mustapha Pasha, the Citadel was originally a military fort, until 1817 year or before the last Dey Ali Khodja decided to make it his residence and the seat of the regency. At the arrival of Hussein Dey at the head of the regency, the Citadel was arranged according to its new role, in seat of the administration it consisted of two palaces, two mosques, a magazine, casemates, and batteries. Transformed from the beginning of the French colonization in 1830 in barracks, the citadel was inhabited by the generals of this army until 1840, year when certain sectors were transformed into military hospital. It was classified in 1887. Part of the citadel was converted in 1930 into a military colonial museum. Today the citadel is undergoing restoration and enhancement work.