The Great Feasts

Feast of Feasts:

Holy Pascha, The Resurrection of the Lord (Easter), the first Sunday that occurs after the first full moon, which follows the vernal equinox, but always after Jewish Passover. 

The Twelve Great Feasts are as follows:

• The Nativity of the Theotokos, September 8 [O.S. September 21]
• The Exaltation of the Cross, September 14 [O.S. 27 September 27]
• The Presentation of the Theotokos, November 21 [O.S. December 4]
• The Nativity of Christ (Christmas), December 25 [O.S. January 7]
• The Baptism of Christ (Theophany, Epiphany), January 6 [O.S. January 19]
• The Presentation of Jesus at the Temple February 2 [O.S. February 15]
• The Annunciation, March 25 [O.S. April 7]
• The Entry into Jerusalem (Flowery/Willow/Palm Sunday), the Sunday before Easter
• The Ascension of Christ, Forty days after Pascha
• Pentecost, Fifty days after Pascha
• The Transfiguration of Jesus, August 6 [O.S. August 19]
• The Dormition of the Theotokos, 15 August [O.S. August 28]

In addition to the Twelve Great Feasts:

• The Circumcision of Christ (January 1 [O.S. January 14])
• The Nativity of St. John the Baptist (June 24 [O.S. July 7])
• The Feast of Saints Peter and Paul (June 29 [O.S. July 12])
• The Beheading of St John the Baptist (August 29[O.S. September 11])
• Intercession of the Theotokos (1 October 1 [O.S. October 14])
  • The Significance of the Shining Veil (orthochristian.com)

Image source: https://legacyicons.com/great-feasts-xxic-icon-f223/