Every morning, several hundred thousand commuters in Istanbul step onto a ferry on one continent and step off, twenty minutes later, on another. The crossing costs roughly the price of a cup of tea. Istanbul is the only major city in the world built astride two continents — its western shore lies in Europe, its eastern shore in Asia — and the ribbon of water between them, the Bosphorus, explains almost everything about its history. The strait is the sole maritime passage between the Black Sea and the Mediterranean; whoever holds it holds a chokepoint on the trade of half a hemisphere. Small wonder the city has been besieged dozens of times, served as capital to two long-lived empires, and answered to three celebrated names.
The first was Byzantium. Around the seventh century BC, Greek colonists from Megara settled the triangular headland where the Bosphorus meets a curving inlet called the Golden Horn. Legend names their leader Byzas, and says the oracle at Delphi told him to build "opposite the land of the blind" — a jab at the earlier settlers of Chalcedon, on the Asian shore, who had somehow overlooked the finest natural harbour in the region. The Golden Horn was that harbour: deep, sheltered and curving some seven kilometres inland. Black Sea grain fleets, fishing boats and, eventually, imperial navies all coveted it, which is why so much of the city's story is the story of defending it.
New Rome
In AD 330 the Roman emperor Constantine the Great rededicated the town as the new capital of the Roman Empire. He called it New Rome, but the world called it Constantinople — Constantine's city. For more than a thousand years it was the seat of the Eastern Roman Empire, which historians later relabelled "Byzantine" after the city's original name — a term its own citizens, who called themselves Romans to the end, never used. Justinian's engineers raised Hagia Sophia in barely five years, completing in 537 what would remain the world's largest cathedral for nearly a millennium, while the triple Theodosian land walls turned back besieger after besieger, from Avars to Arabs.
The harbour had a defence of its own: a massive iron chain, buoyed on floats, that could be winched across the mouth of the Golden Horn to bar enemy fleets. It frustrated attackers for centuries — though the city's most devastating sack, in 1204, came not from its Muslim rivals but from fellow Christians, when the knights of the Fourth Crusade looted Constantinople so thoroughly that the empire never fully recovered.
In 1453 the chain met its match. The Ottoman sultan Mehmed II — just twenty-one years old — battered the land walls with enormous bombards, cannon so heavy that teams of oxen were needed to drag them. Finding the Golden Horn barred, he attempted something audacious: some seventy ships were hauled out of the water and dragged overland on greased timbers, up and over the ridge behind Galata, then refloated inside the chain. After a siege of fifty-three days the walls were breached on 29 May 1453. The last emperor, Constantine XI, died in the fighting; Mehmed took the title Fatih, the Conqueror; Hagia Sophia became a mosque; and the second great empire of the Bosphorus began.
So why "Istanbul"?
Here is the twist that quizzes love: the Ottomans did not rename the city in 1453. Forms of Constantinople — Kostantiniyye on coins and official documents — remained in use for centuries, alongside a colloquial name locals had long been using anyway. "Istanbul" almost certainly derives from the medieval Greek phrase eis tin polin, "to the city": for the Greek-speaking world, Constantinople simply was The City, needing no other name. The exclusive switch came only in 1930, when the young Turkish Republic — which had already moved its capital to Ankara in 1923 under Mustafa Kemal Atatürk — asked foreign post offices to stop delivering mail addressed to Constantinople. A 1953 novelty swing song, "Istanbul (Not Constantinople)", cheerfully finished the job in the world's imagination.
The two shores, meanwhile, were finally stitched together in 1973, when the first Bosphorus Bridge became the first permanent link between the European and Asian sides — though the Persian king Darius had managed a temporary bridge of boats across the strait more than two thousand years earlier, marching against the Scythians. Today the Marmaray rail tunnel carries commuters beneath the seabed itself, and tankers thread the strait past the waterside palaces of sultans.
Three names, two continents, one strait: rulers and titles come and go, but the water that made the city priceless has never moved.
Quiz nuggets
- Istanbul is the only major city on two continents, split between Europe and Asia by the Bosphorus strait.
- Greek colonists from Megara founded Byzantium around the seventh century BC; Constantine rededicated it as his capital in AD 330.
- Constantinople fell on 29 May 1453 to the 21-year-old Ottoman sultan Mehmed II, who had ships dragged overland to bypass the Golden Horn's defensive chain.
- The name Istanbul most likely comes from the Greek eis tin polin — "to the city"; Turkey made it the sole postal name in 1930.
- Istanbul is not Turkey's capital: Atatürk moved the capital to Ankara in 1923.