The tidal-river port the Romans founded as Londinium around 47 CE, which grew into the capital of the largest empire in history and one of the great engines of modern finance, law, the English language, and literature — a metropolis whose splendor was built on industry and on the profits of empire and the Atlantic slave trade, and which survived the loss of both to remake itself as a global financial center and one of the world's most diverse cities.
By 1900, London was the largest city the world had ever seen, the capital of an empire that ruled a quarter of the globe. From a few square miles on the River Thames, its banks and insurers and merchants moved a huge share of the world's trade and capital. That power had a dark engine. The same City that financed railways and factories had earlier financed and insured the Atlantic trade in human beings, and the splendor of the imperial capital stood beside slums that Charles Dickens made famous. London sat near the command center of the imperial world economy and wrote it down, its wealth and its cruelty side by side.