"Geography lies at the basis of history" Immanuel Kant
There is a famous saying in real estate that there are three things that matter in property: location, location, and location. The same is true for cities, and perhaps no city had a better location than Constantinople.
To understand Constantinople's unique location, examine the map below of trade routes during the Middle Ages. You will find Constantinople in the center of the map highlighted by the red arrow. The first thing to notice is that Constantinople is the place where Europe and Asia meet. As a result the city was on the ONLY land route connecting Asia (Middle East, India, China) and Europe. Constantinople is also located at another important crossroads. Built along a narrow strait called the Bosporus , it sits astride the only seaway that connects the Black Sea with the Mediterranean.
As a result of Constantinople's central location at the intersection of continents and Eurasia's two greatest seas, the city was the center of trade routes that connected three continents. From India came spices, pepper and jewels; from Africa came ivory and gold; from Russia came honey, wood, and furs; from Europe came wine, wool, iron, tin, and grain; and from China came silk. In addition to the cities broader strategic location in the world, it also had several local geographic advantages. It had an excellent and spacious harbor known as the Golden Horn. Built on a rocky peninsula, it was surrounded by water on three sides and was easily defended.