September 27 is the Feast of the Elevation of the Holy Cross. After the Crucifixion of Christ, His cross and that of the two thieves crucified with him were lost.
Saint Constantine the Great, Roman Emperor, legalised Christianity within the Empire by the edict of Milan in . He was no doubt influenced strongly by his mother, Empress Helen, who was renowned as a pious Christian.
Amongst her many missions and pilgrimages was the discovery of the cross upon which Christ died, on Golgotha hill in Jerusalem. Tradition states that Empress Helen found a cluster of flowering bushes on Golgotha, known by locals as “Vasilikos” (what we now know as Basil). In Greek, the word “vasil” indicates kingship. Upon excavation beneath the bushes, three crosses were found, along with a sign inscribed with “Jesus of Nazareth, King of the Jews”. To determine which cross was that of Christ, a sick woman kissed each cross and was cured by the last that she kissed. A dead man, being borne to his tomb by a funeral procession, was laid across the same cross and was restored to life. With great joy, the Cross was elevated from a high platform for the whole population of Jerusalem to witness and venerate.
The True Cross was looted from Jerusalem by Persian troops as a trophy in . It took until for Byzantine forces under Emperor Heraclios to retrieve it by force from the Persian capital Ctesiphon, return it to Jerusalem, and to reinstall it in the Church of the Holy Sepulchre .
The Feast on September 27 celebrates both of these events.