We are about to see a Roman emperor in the old Reading Room of the British Museum. Hard on the heels of its highly successful exhibition on China’s first emperor, the museum hosts a show on Hadrian, whose wall in the north of Britain is our answer to China’s Great Wall. The show is part of a series of exhibitions on empires. It is a significant coup for the museum’s visionary director Neil MacGregor and his departmental curators.

In recent years, post-imperial and post-colonial historians have had few positive words for the motives and impact of western empires. It is a neat idea of the British Museum to remind us that there have been many more empires than the British or Spanish and that, often, these empires remain highly praised eras in the national history of countries that most resent the impact of European imperialism on themselves.