Commemoration of the consecration of the Great Church of Hagia Sophia in Constantinople.
On this day the Church remembers the consecration of the Great Church of the Holy Wisdom of God in Constantinople, built by the emperor Justinian in the sixth century. For nearly a thousand years it was the cathedral of the Ecumenical Patriarchate and the greatest church of the Christian world.
Feast day
On the New Calendar, Dedication of Hagia Sophia is commemorated on December 23. Churches on the Old (Julian) Calendar keep the feast on January 5 of the civil calendar.
Also commemorated on December 23

Nahum of Ochrid
Venerable, Ναούμ ο Θεοφόρος
Venerable Nahum the God-bearer, Wonderworker of Ochrid, disciple of Saints Cyril and Methodius.