May 21 - Eastern Orthodox Church calendar - May 23
The First Council of Constantinople (381), wall painting at the church of Stavropoleos, Bucharest, Romania.
First Ecumenical Council of Constantinople (381).
Righteous Melchizedek, King of Salem.
Abraham meets Melchisedech (Mosaic in Basilica di San Marco).
May 20 - Eastern Orthodox Church calendar - May 22
May 22 (Eastern Orthodox liturgics)
…May 21 - Eastern Orthodox Church calendar - May 23 All fixed commemorations below celebrated on June 4 by Orthodox Churches on the Old Calendar…
Sts Constantine and Helena, Holy Equals-to-the-Apostles.
Sts Constantine and Helena, Holy Equals-to-the-Apostles (Mosaic in Saint Isaac's Cathedral, St. Petersburg, Russia).
Stained glass window ( 1986 ) showing St Collen (Llangollen, Wales - St.Collen parish church).
Icon of the Saints of Murom (including Saints Prince Constantine, with Children Michael and Theodore).