Final answer:
Constantinople was renamed Istanbul after it was conquered by Sultan Mehmed II in 1453. Istanbul served as the capital of the Ottoman Empire for centuries.
Step-by-step explanation:
The old capital Constantinople was renamed Istanbul after it was conquered by Sultan Mehmed II in 1453. The city's strategic location between Europe and Asia made it an important trade and political center. Istanbul has a rich history and served as the capital of the Ottoman Empire for centuries.