The city under Ottoman control was enclosed by a wall on all sides, including along the seafront. In this wall, five gates allowed access to the city, with five roads from each gate dividing the city and meeting in front of the Ketchaoua Mosque. In 1556, a citadel was constructed at the highest point in the wall. A major road running north to south divided the city in two: The upper city (al-Gabal, or 'the mountain') which consisted of about fifty small quarters of Andalusian, Jewish, Moorish and Kabyle communities, and the lower city (al-Wata, or 'the plains') which was the administrative, military and commercial centre of the city, mostly inhabited by Ottoman Turkish dignitaries and other upper-class families.