Istanbul

Istanbul is the only great city to straddle two continents — the crowned capital of three vanished empires, with Roman, Byzantine and Ottoman worlds layered under a single street. The Bosphorus runs through its heart like a living artery, carrying ferries and fishermen and a low gold light that settles on a thousand domes and minarets at dusk. You come for Hagia Sophia and the bazaars; you leave remembering the call to prayer rolling across the water, the cats asleep on every wall, and a glass of tea pressed warm into your hand.

Istanbul has been the capital of the world three times over. Founded as Greek Byzantion around 660 BC on the defensible tip where the Bosphorus meets the Golden Horn, it was refounded by Constantine in 330 AD as the New Rome — Constantinople — and for eleven centuries stood as the richest, most populous city in Christendom, its land walls unbreached until the Fourth Crusade sacked it in 1204. In 1453 the twenty-one-year-old Mehmed II took the city after a fifty-three-day siege, and Constantinople became the seat of the Ottoman sultans, who ruled from Topkapı and raised the great imperial mosques that still shape the skyline. The empire fell after the First World War; in 1923 the young republic moved its capital to Ankara, and the city was officially renamed Istanbul in 1930. What makes it singular is that nothing was ever swept away: a Roman column, a Byzantine church turned mosque turned museum, an Ottoman bathhouse and a glass-fronted gallery can share a single street. You never walk through one Istanbul — you walk through all of them at once.

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.