The Citadel of Cairo, also known as the Citadel of Saladin, is a medieval Islamic-era fortress in Cairo, Egypt, built by Salah ad-Din (Saladin) and expanded by subsequent Egyptian rulers. From the 13th to the 19th centuries, it was Egypt's seat of government and the residence of its rulers. Its location on a promontory of the Mokattam hills near Cairo's center commands a strategic position overlooking and dominating the city's skyline. It was one of the most impressive and ambitious military fortification projects of its time when it was built. It is now a preserved historic site, including mosques and museums.