The great mosques of Timbuktu are built of mud brick faced with earth plaster, which the rains take off. They are therefore rebuilt as much as they are maintained, in an annual communal replastering led by the masons' guild, with families bringing earth and water, young men climbing on the projecting wooden stakes that serve as permanent scaffolding, and the work finished as a festival. The building is the same age as the last coat and as old as the practice, which is a different idea of preservation from the one heritage law usually assumes.
Around the mosques stood the tombs of scholars and saints, spoken of collectively as the three hundred and thirty three, visited for blessing and for intercession. In 2012 an armed group took the city and destroyed most of them, along with the sacred door of the Sidi Yahya mosque, on the ground that veneration at graves is idolatry. Manuscripts held at the state institute were burned as the occupiers withdrew.
Two things limited the damage. Librarians and manuscript owners, working quietly over months, moved several hundred thousand volumes out of the city in trunks by road and river to Bamako, a rescue organised largely by the custodial families themselves. And in 2016 the International Criminal Court convicted one of the men responsible for directing the destruction, the first conviction anywhere for the intentional destruction of religious and historic buildings as a war crime, with an order for reparations. The mausoleums were rebuilt by local masons and reconsecrated in 2015.