London
The empire that printed money for two centuries.
Kernel
London is the city that converted Dutch financial innovation, English coal, and a global navy into the first planetary-scale empire. The Bank of England (1694), the East India Company (1600), Lloyd's of London (1688), and the joint-stock corporation form gave Britain a financial operating system that funded steam, rail, telegraphy, and the Royal Navy from one city. At its 1900 peak London was the largest city on earth and the clearing-house for roughly half of world trade.
Why it rose
The Glorious Revolution (1688) imported Dutch finance and a constitutional state. Coal under Yorkshire and Wales powered the steam revolution. The slave-and-sugar Atlantic economy financed the takeoff. The Royal Society (1660) and the Greenwich Observatory (1675) gave London an institutional science it had not previously had. Once steam multiplied per-worker productivity 50-fold (1780–1870), the Empire became financially self-reinforcing.
What it gave the world
The Industrial Revolution as a recognizable phenomenon. The modern joint-stock corporation. Lloyd's-style marine insurance scaled to global shipping. The gold standard (1821–1914). Newtonian physics through the Royal Society. Faraday's electromagnetism. Babbage's analytical engine (a century early). Darwin's evolutionary biology. The Greenwich meridian as a global coordinate system. Telegraphy as a planetary signaling layer.
Why it declined (relatively)
World War I broke the Edwardian financial order. World War II exhausted what was left. The 1956 Suez crisis ended the imperial pretense. New York, Frankfurt, and Tokyo absorbed the financial centrality. London survived as a financial center — the Eurodollar market kept it relevant — but the empire it ran did not. The city is the textbook case of declining as center while continuing as one of the world's three financial hubs.