On September 27 Christians of the Byzantine Rite celebrate the feast of the Exaltation of the Cross or the Holy Cross Day. The holy day is one of the 12 great feasts of the Eastern Church.
The Feast of the Exaltation has a one-day Forefeast and an eight-day Afterfeast. According to historians, the establishment of the festival was based, primarily, on two events: the finding in the 4th century of the Cross on which Jesus Christ was crucified and the return of the cross from Persia to Jerusalem in the 7th century.
The word "exaltation" means a celebratory ritual of veneration and glorification of the Cross of Christ.
The Christian tradition includes several different legends about the finding of the True Cross. Three of them ascribe the finding of the Cross to the mother of Emperor Constantine I, Holy Empress Helena. The True Cross is said to have been discovered in 326. Historians have no information of exaltation of the True Cross right after the discovery.
The feast is originated from the consecration of the Church of the Resurrection of the Lord built by St. Constantine the Great on the Mount of Golgotha in Jerusalem. The church was consecrated at the time of Bishop Makarius of Jerusalem on September 13, 335. On September 14 the True Cross was ceremonially exalted.
In 614, the cross was carried away from the church by the Persians, and remained missing until it was recaptured by the Byzantine Emperor Heraclius in 628. The second ceremonial exaltation of the True Cross in Jerusalem also took place on September 14.
As the feast commemorated Christ's Crucifixion and death and was equaled to the Great Friday, it became a tradition to fast on that day.