Built between 1824 and 1848 in the Turkish style of the mosques of Istanbul, the Mosque of Muhammad Ali is one of the most impressive and spectacular in the Citadel. It is also called "Albastro Mosque" for the material used in the cladding. The arcaded courtyard has a fountain for the ablutions in the center and has a small square tower with clock. The interior of the mosque is bare of any human and divine figuration due to an express prohibition of the Muslim religion. This led artists to develop geometric decorative themes and various forms of arabesque calligraphy to bring the verses of the Koran back to the walls. These scriptures are so elaborate that only specialists can read them.