The Great Mosque of Djenné, Mali a World Heritage Site is the World's Largest Mud-brick Building. It was built around 1908, though a mosque existed at this site from early 13th century. Like the earlier mosque this mosque is also made entirely of mud-brick, mud mortar and mud based plaster. The covered hall is about 50 x 24 metres.
Although not very well known, but after the Sphinx and Pyramids, it is one of the most famous land marks in Africa. Its popularity can be gauged by the fact that two buildings across the world are its replica. More image over here.