When the modern republic of Turkey came into being in the 1920s, Istanbul lost its status as imperial city and capital. But it remains one of the world’s largest, busiest, most vibrant metropoli, its present-day streets, watersides, and bazaars both welcoming and mysterious, its people fully modern, yet deeply aware of their city’s dense, rich history. For people in western Europe, Istanbul has long represented ‘the Orient’, and yet its history has always been as a pre-eminent city in Europe. Its fascination has been that it is the city where Asia meets Europe.

Much of this tour can be undertaken on foot, for the historic centre of the city consists of a small triangle of hilly land (new Rome, like the original city, was built upon seven hills), wedged between the waters of the Golden Horn and the Bosphorus. The Topkapi Palace of the Ottoman sultans occupied the very tip of the triangle. The imperial mosques built by the Ottoman sultans, like the greatest imperial churches, Aghia Sophia in particular, were sited to dominate the skyline. Many other treasures are harder to find, nestling among the modern buildings, their doors opening on narrow streets or small alleyways.

A day on the waters of the Bosphorus sailing up towards the Black Sea puts the city in its geographical setting, and a drive to the defensive walls built by the Emperor Theodosius II provides some indication of the scale.