The Great Mosque of Djenne was built in 1907 and is considered by many architects to be the greatest achievement of the Sudano-Sahelian architectural style, with definite Islamic influences. It is also the largest mud brick building in the world. There was another much older mosque in this site built around the 13th century, but by the 19th century the mosque fell into disrepair and abandoned to thousands of swallows, which build their nests in it. When Seku Amadu conquered Djenne during the Tukulor War, he disapproved the condition the mosque was in, had it closed and built another mosque close by. When French forces led by Louis Archinard captured Djenne in April 1893, he demolished Seku Amadu's mosque and instead built a school in its place, while the original mosque was reconstructed to its current form.
The walls of the Great Mosque are made of sun-baked mud bricks called ferey, a mud based mortar, and are coated with a mud plaster which gives the building its smooth, sculpted look. The walls are between 41 cm (16 in.) and 61 cm (24 in.) thick - the thickness varying with the wall's height. Bundles of palm branches were included in the building to reduce cracking caused by frequent drastic changes in humidity and temperature and to serve as readymade scaffolding for annual repairs. The walls insulate the building from heat during the day and by nightfall have absorbed enough heat to keep the mosque warm through the night. Gutters, made of ceramic pipes, extend from the roofline and direct water drainage from the roof away from the walls. To protect the Great Mosque from water damage, in particular flooding by the Bani river, the entire structure was constructed on a raised platform 3 meters high. A set of six stairs, each decorated with pinnacles, leads to the mosque's entrance.
Annual repair of the mosque is almost a festival and the entire community of Djenne takes an active role in it. In the days leading up to the festival, the plaster is prepared in pits. It requires several days to cure but needs to be periodically stirred, a task usually falling to young boys who play in the mixture, thus stirring up the contents. Men climb onto the mosque's built-in scaffolding and ladders made of palm wood and smear the plaster over the face of the mosque.
Another group of men carries the plaster from the pits to the workmen on the mosque. A race is held at the beginning of the festival to see who will be the first to deliver the plaster to the mosque. Women and girls carry water to the pits before the festival and to the workmen on the mosque during it. Elderly members of the community sit in the market square watching the proceedings. Music and food is included during the festival.
The mosque used to welcome infidel but in 1996 permission was granted to French Vogue for a fashion shoot inside the building. The insensitive photographs of semi-naked women horrified the mullahs and non believers have been denied access ever since.
The historic areas of Djenne, including the Great Mosque, were designated a World Heritage Site by UNESCO in 1988. While there are many mosques that are older than its current incarnation, the Great Mosque remains the most famous landmarks of the twon and the entire nation of Mali.