Why was constantinople the perfect city trade ? what evidence do you see?

Constantinople was the capital of the Byzantine Empire. It was one of the largest and wealthiest urban areas in the Eastern Mediterranean.  Its strategic location played an important role in its success. Constantinople commanded the trade routes between the Aegean Sea and the Black Sea. It had a powerful cultural influence and dominating economic life. Its architecture attracted people from many places. It got to be known as the 'Queen of Cities'

No wonder Constantinople was a massive trade hub. Another evidence is the fact that the famous Silk Road ran through the city.

a. always outside of government control.