The Great Friday Mosque, JenneThe mosque at Jenne was built in the form of a parallelogram. Inside, nine long rows of adobe columns run along a north-south axis and support a flat roof of palm logs. A pointed arch links each column to the next in its row, forming nine east-west archways facing the mihrab, the niche in the wall of the mosque indicating the direction of Mecca, and from which the imam speaks. This mosque (rebuilt in 1907 based on the original thirteenth-century structure) testifies to the considerable wealth, geometrical knowledge, and manpower of Mali. (Gerard Degeorge/akg-images)