Nicaea, known today as Iznik, was an important city in the Ottoman Empire. It served as a significant administrative and cultural center, especially during the early years of Ottoman rule. The city is historically notable for hosting the First Council of Nicaea in 325 AD, which addressed key issues in early Christianity. Under Ottoman control, Nicaea experienced architectural and economic development. The Ottomans built mosques, madrasas, and other structures, reflecting their Islamic heritage. The city became a hub for trade and agriculture, contributing to the prosperity of the region within the empire.