Question

What was the importance of Constantinople?

Answer 1

It was the capital of the Eastern Roman Empire, but also, "closer to the action" as it were. The idea of Rome as the center of the world had long passed with the changing world of the Mediterranean in the centuries after Constantine's rise to power. Its role as a vital trade city uniting the far east with the "West" also gave it an advantage as it overlooked an important water route from Asia and the Middle East to the rest of Europe.

Politically, it was also the seat to the emperor of the Eastern Roman Empire. The Empire, by that point, had split into East and West with essentially had two rulers.