The Largest Mudbrick Building on Earth, Rebuilt Every Year

The Great Mosque of Djenne is built entirely from banco, a local mixture of mud and straw applied over a timber and palm-rib frame, a construction technique that makes the mosque simultaneously one of the most striking works of religious architecture in West Africa and one of the most demanding to maintain. Mudbrick construction is vulnerable to erosion by seasonal rain in a way that fired brick or stone is not, and rather than treat that vulnerability as a design flaw to be engineered away, the people of Djenne turned the mosque's upkeep into a communal religious institution in its own right, the annual Crepissage, in which residents organized by neighborhood collect fresh mud, mix it, and replaster the entire exterior surface by hand in a single coordinated festival.

The Crepissage is not simply maintenance performed out of necessity; it is treated locally as a civic and religious occasion, an annual reaffirmation of the community's collective responsibility for its central mosque that a permanent, weatherproof building would never require or produce. Few religious structures anywhere make a community's ongoing physical labor as literally load-bearing a part of their continued sanctity as Djenne's does, since without the yearly replastering the building itself would not survive the next rainy season.