Nicæa, known today as İznik, is a historic city in northwestern Turkey. It was significant in ancient times, particularly as the site of the First Council of Nicæa in 325 AD, which was convened by Emperor Constantine to address issues within the early Christian church. The city is also famous for its beautiful Lake Nicæa and well-preserved ancient walls. Nicæa played a crucial role in the development of early Christian doctrine and was a center of trade and culture during the Byzantine Empire. Its rich history continues to attract visitors and scholars alike.