The correct answer to this open question is the following.
The role that Constantinople played in medieval Europe’s economy until the 12th century was of the main hub or center for trade.
In that time, Constantinople, the capital of the Byzantine Empire, was the most important city in the region. Many merchants for all over Europe, Asia, and North Africa, and even India gathered in Constantinople to trade their goods. Constantinople was a modern metropolis for that time that had beautiful architecture and modern services to host such a diverse combination of ethnicities
Constantinople has the most strategic locations. It was near the Mediterranean Sea, and most of the trade spots are located in this area. The city lives for trade and the empire had made sure that they will be able to protect their economy from any barbaric intrusion. Because of this, Constantinople became the major spot for commerce until the 12th century
