Few major cities, if you turn back the clock, were also significant 500 or 1,500 years ago. In 500 AD, New York, Moscow and Sao Paulo didn’t exist. But Istanbul, then known as Constantinople, was the capital of the Byzantine Empire — and today it remains Turkey’s largest city and one of the most populous metro areas in the world. It’s also an ideal place to visit, located right smack on the dividing line between Europe and Asia, with a wealth of historical and religious sites, bazaars, a rich food culture and nearby islands accessible via ferry rides. Photographer and GP contributor Isaac Zapata recently explored the city, which he called “a clash of beauty, history and a controlled sort of chaos”.