Pedestrians and an electric tourist shuttle move along the road flanking the massive alabaster and limestone outer wall of the Muhammad Ali Mosque (Mosque of Muhammad Ali Pasha) inside the Cairo Citadel (Qal'et Salah El-Din), a medieval Islamic fortification built by Salah El-Din Al-Ayyubi in the 12th century. The mosque's Ottoman-style silver domes and slender minarets rise prominently against a partly cloudy sky. The Citadel has served as the seat of Egyptian government for nearly 700 years and remains one of Cairo's most visited historic landmarks.