Constantinople: The capital city of both the Byzantine Empire and later the Ottoman Empire after its conquest by Mehmed II. It served as an economic, cultural, and strategic center for centuries.
Ottoman Empire: A powerful state originating from Anatolia (modern-day Turkey) that expanded through military conquests to become a major empire during its peak in the 16th and 17th centuries.
Byzantine Empire: The Eastern Roman Empire that survived after the fall of Western Rome. Constantinople was its capital, and it preserved many aspects of ancient Greek and Roman culture while developing into a distinct Byzantine civilization.