Ancient Nicæa, located in present-day Iznik, Turkey, was a significant city in the Roman Empire. It is best known for hosting the First Council of Nicæa in 325 AD, which aimed to address divisions within early Christianity and resulted in the formulation of the Nicene Creed. The city was strategically positioned near the shores of Lake Ascania, making it an important trade and military hub. Throughout its history, Nicæa was influenced by various cultures, including the Greeks and Byzantines. The city features several historical sites, such as the Walls of Nicæa and the Hagia Sophia of Nicæa, which reflect its rich architectural heritage and significance in religious history.