The capital of the Ottoman Empire was Constantinople, which is now known as Istanbul. The city was conquered by the Ottomans in 1453 under the leadership of Sultan Mehmed II, marking the end of the Byzantine Empire. Constantinople served as the cultural, political, and economic center of the Ottoman Empire, strategically located along trade routes between Europe and Asia. Its rich history and diverse population contributed to a flourishing of arts, architecture, and scholarship, with notable landmarks including the Hagia Sophia and the Topkapi Palace.