This is from the OCA website about today's major feast day which is always celebrated on September 14th. The icon image above is also from the same website.
Here is the history of this day:
The Elevation of the Venerable and Life-Creating Cross of the Lord: The pagan Roman emperors tried to completely eradicate from human memory the holy places where our Lord Jesus Christ suffered and was resurrected for mankind. The Emperor Hadrian (117-138) gave orders to cover over the ground of Golgotha and the Sepulchre of the Lord, and to build a temple of the pagan goddess Venus and a statue of Jupiter.
Pagans gathered at this place and offered sacrifice to idols there. Eventually after 300 years, by Divine Providence, the great Christian sacred remains, the Sepulchre of the Lord and the Life-Creating Cross were again discovered and opened for veneration. This took place under the Emperor Constantine the Great (306-337) after his victory in the year 312 over Maxentius, ruler of the Western part of the Roman empire, and over Licinius, ruler of its Eastern part. In the year 323 Constantine became the sole ruler of the vast Roman Empire.
In 313 he had issued the Edict of Milan, by which the Christian religion was legalized and the persecutions against Christians in the Western half of the empire were stopped. The ruler Licinius, although he had signed the Edict of Milan to oblige Constantine, still fanatically continued the persecutions against Christians. Only after his conclusive defeat did the 313 Edict of toleration extend also to the Eastern part of the empire. The Holy Equal of the Apostles Emperor Constantine, having gained victory over his enemies in three wars with God's assistance, had seen in the heavens the Sign of the Cross, and written beneath: "By this you shall conquer."
Ardently desiring to find the Cross on which our Lord Jesus Christ was crucified, St Constantine sent his mother, the pious Empress Helen (May 21), to Jerusalem, providing her with a letter to St Macarius, Patriarch of Jerusalem.
Although the holy empress Helen was already in her declining years, she set about completing the task with enthusiasm. The empress gave orders to destroy the pagan temple and the statues in Jerusalem. Searching for the Life-Creating Cross, she made inquiry of Christians and Jews, but for a long time her search remained unsuccessful.
Finally, they directed her to a certain elderly Hebrew by the name of Jude who stated that the Cross was buried where the temple of Venus stood. They demolished the pagan temple and, after praying, they began to excavate the ground. Soon the Tomb of the Lord was uncovered. Not far from it were three crosses, a board with the inscription ordered by Pilate, and four nails which had pierced the Lord's Body (March 6).
In order to discern on which of the three crosses the Savior was crucified, Patriarch Macarius alternately touched the crosses to a corpse. When the Cross of the Lord touched the dead one, he came to life. Having beheld the raising of the dead man, everyone was convinced that the Life-Creating Cross was found.
Christians came in a huge throng to venerate the Holy Cross, beseeching St Macarius to elevate the Cross, so that even those far off might reverently contemplate it. Then the Patriarch and other spiritual leaders raised up the Holy Cross, and the people, saying "Lord have mercy," reverently prostrated before the Venerable Wood. This solemn event occurred in the year 326.
During the discovery of the Life-Creating Cross another miracle took place: a grievously sick woman, beneath the shadow of the Holy Cross, was healed instantly. The elder Jude and other Jews there believed in Christ and accepted Holy Baptism. Jude received the name Cyriacus and afterwards was consecrated Bishop of Jerusalem.
During the reign of Julian the Apostate (361-363) he accepted a martyr's death for Christ (see October 28). The holy empress Helen journeyed to the holy places connected with the earthly life of the Savior, building more than 80 churches, at Bethlehem the birthplace of Christ, and on the Mount of Olives where the Lord ascended to Heaven, and at Gethsemane where the Savior prayed before His sufferings and where the Mother of God was buried after her death.
St Helen took part of the Life-Creating Wood and nails with her to Constantinople. The holy emperor Constantine gave orders to build at Jerusalem a majestic and spacious church in honor of the Resurrection of Christ, also including under its roof the Life-Giving Tomb of the Lord and Golgotha. The temple was constructed in about ten years. St Helen did not survive until the dedication of the temple, she died in the year 327. The church was consecrated on September 13, 335. On the following day, September 14, the festal celebration of the Exaltation of the Venerable and Life-Creating Cross was established.
Another event connected to the Cross of the Lord is remembered also on this day: its return to Jerusalem from Persia after a fourteen year captivity. During the reign of the Byzantine emperor Phocas (602-610) the Persian emperor Khozroes II in a war against the Greeks defeated the Greek army, plundered Jerusalem and captured both the Life-Creating Cross of the Lord and the Holy Patriarch Zachariah (609-633).
The Cross remained in Persia for fourteen years and only under the emperor Heraclius (610-641), who with the help of God defeated Khozroes and concluded peace with his successor and son Syroes, was the Cross of the Lord returned to the Christians.
With great solemnity the Life-creating Cross was transferred to Jerusalem. Emperor Heraclius in imperial crown and royal purple carried the Cross of Christ into the temple of the Resurrection. With the emperor went Patriarch Zacharios. At the gates by which they ascended Golgotha, the emperor suddenly stopped and was not able to proceed farther. The holy Patriarch explained to the emperor that an angel of the Lord was blocking his way. The emperor was told to remove his royal trappings and to walk barefoot, since He Who bore the Cross for the salvation of the world from sin had made His way to Golgotha in all humility. Then Heraclius donned plain garb, and without further hindrance, carried the Cross of Christ into the church.
In a sermon on the Exaltation of the Cross, St Andrew of Crete (July 4) says: "The Cross is exalted, and everything true gathers together, the Cross is exalted, and the city makes solemn, and the people celebrate the feast".