Nicaea
A city of Bithynia in north-western Asia Minor, on the shore of a lake. Constantine gathered the bishops here in 325 for the first general council of the church, and a second council met here in 787.
Nicaea stood at the eastern end of Lake Ascania in Bithynia, a short journey from the imperial residence at Nicomedia. Eusebius remarks that its name, from the Greek word for victory, suited the occasion when Constantine chose it for the council of 325 (Eusebius, Life of Constantine 3.6). The bishops met in the largest hall of the palace there (Eusebius, Life of Constantine 3.10). The town is modern İznik. See the First Council of Nicaea and, for the council of 787, the Second Council of Nicaea Restores Icons.
What happened here
- May AD 325, firm dateThe First Council of Nicaea
Constantine gathers some three hundred bishops at Nicaea over the teaching of Arius. They confess the Son to be “of one substance with the Father”, agree a common date for Easter and issue twenty canons. Catholic, Orthodox and Reformation churches still appeal to the council.
- AD 787, firm dateThe Second Council of Nicaea Restores Icons
A council called by the empress Irene and led by the patriarch Tarasius, with legates of Pope Hadrian I, overturns the iconoclast council of 754. It decrees that images are to be set up and honoured, and that worship in the full sense belongs to God alone.
- 28 November 2025, firm dateThe Churches Mark 1,700 Years since Nicaea
Pope Leo XIV, the Ecumenical Patriarch Bartholomew and leaders of other churches pray together at İznik, the ancient Nicaea, and profess the creed. The next day pope and patriarch sign a declaration naming the faith of Nicaea as what binds Christians together.