The Great Mosque of Djenné in Mali stands on a platform about 75 by 75 meters, raised three meters above the market to stay dry when the Bani River floods. It is built of sun-dried ferey bricks set in sand and earth mortar and coated in plaster, with toron, bundles of palm sticks jutting 60 centimeters from the walls, serving as permanent scaffolding. Three minarets on the qibla wall reach up to 16 meters and are topped with ostrich eggs, and the dim prayer hall rests on 90 pillars because mud cannot span wide spaces. Removable ceramic bowls vent hot air and ceramic half pipes throw rainwater clear of the walls.

The Tarikh al-Sudan credits Sultan Kunburu with tearing down his palace to build the first mosque, dated between 1200 and 1330. Around 1818 the Fulani reformer Sekou Amadou let it melt in the rain and built a plain mosque nearby. René Caillié found the ruins full of swallows in 1828, and in the 1890s Félix Dubois saw them used as a cemetery. In 1906 and 1907 mason guild head Ismaila Traoré rebuilt it with forced labor supplied by the French, and Dubois later mocked it as a hedgehog crossed with a church organ, though scholars credit its design to local builders.

• Why mud’s strength in compression and weakness in tension forced a forest of pillars
• The annual replastering festival, from boys splashing in mud pits to a race to deliver the first plaster
• Djenné’s refusal of plumbing and tiles that have damaged other historic Malian mosques
• The January 2006 riot after an Aga Khan Trust team was seen on the roof
• More than three inches of rain in 2009 bringing down the top of the southern tower