The Feast of the Cathedral of Holy Etchmiadzin is celebrated in Armenia on June 7, occurring sixty-four days after Easter. This religious holiday commemorates the Etchmiadzin Cathedral, the first cathedral built in ancient Armenia, located in Vagharshapat. According to legend, the cathedral was established by Saint Gregory the Illuminator, who had a vision of Jesus Christ indicating the site for its construction. The original structure was completed around 303, with significant additions made in the 480s and 1868. In 2000, the cathedral was designated a UNESCO World Heritage Site. During the feast, a special hymn composed in the 8th century by Sahak III of Dzorapor, which recounts Saint Gregory's vision and the cathedral's construction, is sung.