According to the legend, one day Gregory the Illuminator had a dream that Jesus Christ, with a golden hammer in his hand, descended from heaven and struck where the pagan temple was. In the morning, Gregory the Illuminator retold his dream to King Trdat, who built a temple there called “Etchmiadzin” – Descend of the Only Begotten. And the Only Begotten is the Messiah of Christ.

According to historian Agatangeghos, the Mother Cathedral of Etchmiadzin was built near royal palaces during the reigns of Trdat III (298-330) Gregory the Illuminator, in the first years when Christianity was declared a state religion in Armenia:301-303.