Dan Fodio's son, Muhammed Bello, established the empire's capital in Sokoto and it has remained the centre of Nigerian Islam ever since, with its huge mosque opposite the sultan's palace.

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Part Gothic cathedral, part Teutonic fortress, part sultan's palace, its roofline is a riot of spires, beehive water towers and gaudily tiled domes, and its flanks are decorated with heraldic symbols and heroic-scale frescoes of the hospital's benefactors.

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Our reporter says the crowds of mourners are likely to remain outside the sultan's palace for many weeks - some travelling from neighbouring Niger and other West Africa countries with large Muslim populations, such as Chad, Mali and Senegal.

BBC: The Sultan of Sokoto Mohammadu Maccido

Six pictures have been loaned by the Tate to Sultan Qaboos' Al-Alam palace in the Omani capital of Muscat.

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After the appointment of the next sultan, the crowds outside the palace are likely to further increase, now mixing their condolences with congratulations.

BBC: The Sultan of Sokoto Mohammadu Maccido

And at the Topkapi Palace, surely the chefs rose above kebabs and mezes to keep the sultan well fed?

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But the hapless pasha was decapitated, his severed head being duly placed in a gourd full of honey and exposed at the Topkapi palace in Istanbul, after he was implicated in a plot to overthrow the sultan.

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