Ізніку, also known as Nicaea, is a historic city located in northwestern Turkey. It was an important center in ancient times, known for its strategic location near the Bithynia region. The city is famous for hosting the First Council of Nicaea in 325 AD, which was a significant event in early Christianity that addressed key theological disputes. Today, Ізніку is recognized for its rich cultural heritage, including well-preserved ruins and beautiful landscapes. The city features notable sites such as the Hagia Sophia of Nicaea and ancient city walls, attracting visitors interested in history and architecture.