Location:

 12.5 miles from downtown. 

Who built it?

The citadel was constructed by Salah El Din on the Moqattam hills in 1183 AD overlooking the whole city to be his defensive point against the attacks of the Crusaders. Salah El Din appointed to be the governor of Egypt after the death of the Sultan of Damascus, Noor-el-Din. 

Why was it built ?

It was built to defend Cairo from the armies of the Crusaders 573 AH and to become the center of Salah El Din's government. Explanation: After the death of Salah El Din, his nephew, Al Kamel, reinforced the Citadel by enlarging several of the towers. The citadel has two entrances : one opening on Salah Salem road and the other is the old gate that has existed since Salah El Din's age.