The First Council of Nicaea was a council of Christian bishops convened in the Bithynian city of Nicaea (now Iznik, Bursa province, Turkey) by the Roman Emperor Constantine I in AD 325. Constantine I organized the Council along the lines of the Roman Senate and presided over it, but did not cast any official vote.
This ecumenical council was the first effort to attain consensus in the Church through an assembly representing all of Christendom. Hosius of Cordoba, who was probably one of the Papal legates, may have presided over its deliberations.
Its main accomplishments were settlement of the Christological issue of the divine nature of the God the Son and his relationship to God the Father, the construction of the first part of the Nicene Creed, establishing uniform observance of the date of Easter, and promulgation of early canon law.