This mosque is the largest with its age and with respect to its state of conservation and its place of origin in Egypt. It was built between 876 and 879 of our era.
   It is an almost square building with 160 m long on each side. Even a wall that runs through three of its sides forming a three-sided corridor. The mosque itself is rectangular measuring 118 X 138 meters.
   It has 760 columns; every four columns are grouped together to form a pillar, they are made of stuccoed brick and the capitals are decorated with leaves in which Byzantine influences are evident.
   On the plaster frieze, decorated with plant motifs, runs another wooden one in which an inscription in Kufic characters has been engraved that reproduces a part of the Koran (the chapters of Al-Baqarah and A'al Emran), which measure more than two kilometers. According to tradition, the wood on which this inscription is carved comes from Noah's ark, found by Ibn Tulún on Mount Arafat when he was on pilgrimage. The exterior wall is open on all four sides by windows and skylights, there are 128 in total and offer a great variety of shapes to the point that no two are alike.