The Columbia Encyclopedia, Sixth Edition. Columbia Encyclopedia World Factbook American Heritage Coll.
Most mosques have one or more small towers, which are usually placed at the corners.
The square form remained in use in Syria until the 13th cent. The free-standing conical minaret surrounded by a spiral staircase, probably deriving from the ancient Babylonian ziggurat, was built at Samarra, Iraq, and in Cairo in the second half of the 9th cent. See Islamic art and architecture . The Columbia Encyclopedia, Sixth Edition.