Houses of prayer for the followers of Islam are called mosques. They vary in design, usually being built of stone and wood but they all have certain essential common features necessary for correct religious practice.
Mosques are usually designed around a central courtyard in which there must be a well or fountain for the necessary washing before prayer. The sides of the courtyard are often porticoed. Minarets are usually built on the corners of the courtyard and, from the balcony on the minaret, the faith-full are called to prayer by a crier, the muezzin. In the prayer hall is the mihrab, or prayer niche, which is always in the qiblah wall, that is, the wall facing Mecca. The services are conducted from a platform near which is the pulpit, or mimbar. The origin of the design of the first mosque, in Mecca, was probably Abyssinian. In the first century AD, when the Muslims were conquering towns in the Near East, they usually took one of the existing churches and converted it into a mosque. This was usually done by blocking up some doors, inserting the main door in the north wall and arranging to pray in the direction of Mecca. During this time, the mosque was also the assembly hall, a place where decisions affecting Islam were made.
In later years, mosques became more elaborate, some havin gmore than one mihrab and the prayer hall being covered by a dome. The pillars, walls and floors were usually intricately decorated. Floors were paved with marble or mosaics, walls were paneled and decorated with friezes, and pillars were delicately carved, the capital indicating the country of origin. Arches were either a rounded or pointed horseshoe shape and the decorative carving was either geometric, based on the hexagon or octagon, or flowing, the design sometimes including God's name or a religious phrase in stylized form. Floral designs were often used in carved marble or plaster. Some of the most famous mosques are the Great Mosque of Damascus, regarded by medieval Muslims as one of the wonders of the world; the Great Mosque of Kairouan, built in the desert of Tunisia and showing the influence of all of the surrounding nations; and the Al Aqsa Mosque in Jerusalem.