Final answer:
The capital of the Eastern Roman Empire was Constantinople, founded by Emperor Constantine and known for its strategic location and significance in trade and power.
Step-by-step explanation:
When the Roman Empire was split into two separate empires, the capital of the Eastern Roman Empire was the city of Constantinople. Emperor Constantine the Great founded this city on the site of the ancient Greek city of Byzantium in 324 CE and officially dedicated it in 330 CE. Constantinople was strategically located at the juncture between Europe and Asia, controlling vital trade routes between the two continents and over the Bosphorus Strait. After the fall of the Western Roman Empire in 476 CE, Constantinople remained the center of the Eastern Roman Empire, also known as the Byzantine Empire, continuing to thrive as one of the most important cities in Europe during the Middle Ages.