View of the ancient limestone fortification walls and archaeological excavation terraces of the Cairo Citadel (Qalat Salah El-Din), located in the Al-Khalifa district, Cairo. The Mohamed Ali Mosque (Gamal El-Din Al-Dhahabi Mosque), commonly known as the Alabaster Mosque, dominates the skyline atop Mokattam Hill with its Ottoman-style central dome and four minarets. The Citadel was originally built by Salah El-Din Al-Ayyubi in the 12th century and served as the seat of Egyptian government for nearly 700 years.