Final answer:
The two capitals of the divided Roman Empire were Constantinople and Rome. Constantinople later became known as Istanbul, the modern city in Turkey, after the fall of the Byzantine Empire.
Step-by-step explanation:
After the Roman Empire was divided, the two capitals were Constantinople and Rome. Constantinople, known as Byzantium before Emperor Constantine renamed it after himself in 330 CE, became the capital of the Eastern Roman Empire and played a crucial strategic role due to its location controlling the Bosphorus and Dardanelles straits. This city positioned the Eastern Roman Empire, or the Byzantine Empire, at a significant crossroads for trade between Europe and Asia.
On the other hand, Rome continued to be the capital of the Western Roman Empire until its decline. It's worth noting that Constantinople is the ancient name for what became known as Istanbul after it was conquered by the Ottoman Turks in 1453 CE.