Istanbul

Istanbul spent eleven centuries as the eastern capital of Rome — Christian, Greek-speaking, later called Byzantine — and five more as the Ottoman seat, and both are still underfoot. Aqueduct arches stand over traffic, a sixth-century church hides behind a tram stop, vegetable gardens grow at the base of the land walls. The Bosphorus that splits the city between Europe and Asia is a working waterway rather than a view; ferries cross it the way other cities ride the metro, and changing continents costs a token and twenty minutes. Around sixteen million people live here, yet the historic core is compact enough to walk end to end in a morning — the crowding is real, and so is the ease of escaping it by water.

For nearly sixteen unbroken centuries, from 330 to 1923, this was the capital of an empire. Greek settlers founded Byzantion around 660 BC on the defensible tip where the Bosphorus meets the Golden Horn. Constantine refounded it in 330 AD as the New Rome, Constantinople, and for eleven centuries it stood as the richest, most populous city in Christendom. Its land walls were not breached until the Fourth Crusade sacked the city in 1204. In 1453 the twenty-one-year-old Mehmed II took the city after a fifty-three-day siege, and the Ottoman sultans ruled from Topkapı and raised the imperial mosques that still shape the skyline. The empire fell after the First World War; in 1923 the republic moved its capital to Ankara, and the city was renamed Istanbul in 1930. Nothing was ever swept away, and the layers lie unevenly. Sultanahmet is Byzantine ground under Ottoman glaze; Balat and Fener still carry the names of the Greek and Jewish families who built them. Kadıköy is older than all of it: Chalcedon was planted on the Asian shore seventeen years before Byzantion, and mocked ever after as the town of the blind for choosing the wrong side of the water.

Three days covers the historic peninsula and a Bosphorus crossing; five lets you slow down for the Asian side, the back-street bazaars, and a ferry taken with no plan at all.