ketchaoua mosque is a mosque in algiers, the capital of algeria. it is located at the foot of the casbah, which was built during the ottoman rule in the 17th century, which is a unesco world heritage site. the mosque that stands on the first of the casbah's many steep stairways, was logistically and symbolically the cynosure of the pre-colonial city of algiers. the mosque is noted for its unique fusion of moorish and byzantine architecture.