“Every year the whole community works together to replaster the mosque,” explains Fané Yamoussa, a local Malian historian. “We start at sunrise after morning prayers and by lunch it’s finished.” The dry months of January to March are the building season in Djenné, an ancient city in the Niger river’s vast inland delta. Its Great Mosque is the world’s largest mud building—and the reason for UNESCO naming the city as a world monument in 1988.
The minarets are 18 metres (59 feet) tall. The fortress-like walls are pierced with palm-wood beams. Every year in April, before the rains arrive, is the crépissage, when new mud is smeared over old walls. The city’s chief replasterers, some 80-strong, belong to a centuries-old guild called the barey ton. As one puts it, “a good mason knows the building and the spirits.”