Istanbul

Inhabited for more than 2,500 years, the old walled city of Istanbul was one of the most coveted places in the world. To resist invaders, its inhabitants built massive walls, 5 meters (16 feet) deep and 9 meters (30 feet) in height. 

Yet, the walls were more like an invitation, a signal that something worth taking hid within its walls. Formerly known as Constantinople, and before that as Byzantium, Istanbul was founded at a crossroad between Europe and Asia, Christianity and Islam. 

It was the capital city of the Roman, Byzantine, and Ottoman Empires and briefly the capital city of the Turkish Republic, each opening the city's doors to friends and firmly shutting them to enemies. 

The city was attacked more than 60 times. In ancient times, the Greeks, Athenians, Persians, and Spartans fought to capture it; so did the Gauls and the Macedonians. 

The Romans finally took it and renamed it after Constantine the Great, who declared it the new capital of a united Roman Empire. Something about this city by the water compelled its leaders to spare no efforts in aggrandizing it. 

The Byzantine Empire spent countless fortunes building palaces, churches, and other buildings. So did the Ottoman Empire, which captured the city in 1453 and proceeded to cover the city with palaces, mosques, and water fountains. Their efforts stood in stark contrast with those who were left outside the walls. 

Those who penetrated its walls by force took great pleasure in tearing the city down, stealing its treasures and hauling anything that could be carried back home across long distances. What man could not destroy, nature took away. 

Dozens of earthquakes have shaken the city throughout its history, turning buildings to dust. Like many cities in the world, Istanbul long ago lived its golden era. Today, it is poverty, pollution, and social problems that besiege the city. Yet, Istanbul retains its exuberance, its charm, and its place in history.