Opening of the First Council of Nicaea

Date: May 20, 325 • Location: Rome, Italy

The First Council of Nicaea is formally opened, starting the first ecumenical council of the Christian Church.

The First Council of Nicaea was a council of Christian bishops convened in the Bithynian city of Nicaea by the Roman Emperor Constantine I, also known as the First Ecumenical Council. It met from May until the end of July 325.