Istanbul, and the city with three names

Few cities can claim to have been the capital of three different empires without moving an inch. Istanbul managed it by sitting in an unusually useful spot: on the Bosphorus, the strait that separates Europe from Asia and connects the Black Sea to the Mediterranean, a position that made whoever controlled it rich from trade and vulnerable to everyone who wanted a share of it.

A Greek colony called Byzantium

The city began, around the seventh century BC, as Byzantion, a colony founded by Greek settlers who recognised a natural harbour and a defensible peninsula when they saw one. For the best part of a thousand years it was a significant but not dominant city in the Greek and then Roman world, until the Roman emperor Constantine chose it in the fourth century AD as the site for a new, eastern capital, and renamed it after himself.

Constantinople, capital twice over

Constantinople went on to serve as capital of the Roman Empire and then, after Rome itself fell in the west, as capital of what historians call the Byzantine Empire, the Greek-speaking, Christian continuation of Roman rule that lasted another thousand years from the Bosphorus. Constantine had the city laid out, deliberately, across seven hills in imitation of Rome itself, a piece of urban planning meant to signal continuity rather than a fresh start. The Hagia Sophia, built in the sixth century under the emperor Justinian, is the great surviving monument of that era: an enormous domed cathedral, engineered at the very edge of what contemporary builders understood to be possible, and unmatched in scale for centuries afterwards.

The thousand years were not entirely unbroken. In 1204, soldiers of the Fourth Crusade, diverted from their original destination by a dispute over payment and succession, sacked Constantinople itself, installing a short-lived Latin Empire that held the city for roughly half a century before Byzantine rule was restored. The episode weakened the empire considerably, and historians generally count it among the reasons Constantinople was in no position to resist the Ottomans two and a half centuries later.

That thousand-year run ended in 1453, when Ottoman forces under Sultan Mehmed II took the city after a prolonged siege, ending the Byzantine Empire and beginning nearly five centuries of Ottoman rule. The Hagia Sophia was converted into a mosque within days of the conquest; it later became a museum in the twentieth century, and was reconverted to a working mosque in 2020, a chain of changes that says a good deal about how the building has always tracked whoever held the city.

Istanbul, officially

The Ottomans built their own layer on top of the Byzantine one, most visibly at Topkapi Palace, the sultans' residence and seat of government for roughly four centuries, and at the mosques that punctuate the skyline, several of them deliberately answering Hagia Sophia's dome with domes of their own. The name Istanbul had been in informal use for the city for centuries before it became official; the Turkish Republic, founded in the 1920s after the Ottoman Empire's collapse, formally adopted it in 1930, closing the loop on a city that had already been called by that name, more or less, by ordinary residents for a very long time.

Just outside the modern city, Bursa is worth remembering too: it was the first capital of the fledgling Ottoman state in the fourteenth century, before Constantinople itself was captured, and its mosques and tombs are a quieter, earlier chapter of the same story that ends at Topkapi.

A city built to be read in layers

None of Istanbul's history has been tidied away to make room for the next chapter, which is what makes the city rewarding rather than merely old. A single afternoon can move from a Byzantine cistern, built to store water for a Roman-era city, to an Ottoman mosque built five hundred years later on the site of an earlier church, to a modern ferry terminal doing the same job the Byzantines and the Ottomans both relied on the Bosphorus to do. Three names, three empires, and a strait that has never really stopped being the point of the whole exercise.