Istanbul
The city straddling Europe and Asia across the Bosphorus
Istanbul is the rare metropolis that sits on two continents, its sixteen million people spread across the Bosphorus strait that separates Europe from Asia. For sixteen centuries it was an imperial capital under three names and three empires, and the skyline still carries that weight: the great dome of Hagia Sophia, the cascading domes and slender minarets of the Blue Mosque, the sprawling courtyards of Topkapi Palace. Ferries crisscross the water between the two halves of the city all day long.
The historic core occupies a hilly peninsula between the Sea of Marmara and the deep natural inlet of the Golden Horn, with the Bosphorus channel curling north toward the Black Sea. This strait is one of the world's busiest and most strategic waterways, the only sea route between the Black Sea and the Mediterranean, and bridges and a tunnel now stitch the European and Asian shores together. The land is seismically active, and a major fault offshore in the Marmara shadows the city's future.
Founded by Greek colonists as Byzantium around the seventh century BCE, the city was refounded by Constantine in 330 CE as Constantinople, capital of the eastern Roman and Byzantine empire, and then of the Ottomans after their conquest in 1453. Each empire layered it with churches, mosques, palaces, and bazaars. Though Ankara became the Turkish republic's capital in 1923, Istanbul remains the country's largest city, its cultural and economic heart, and a crossroads of trade and migration between Europe, the Middle East, and Asia.