The Triumph of the Holy Cross - 14th September...
In the Western Church the feast came into prominence in the seventh century — after 629, when the Byzantine emperor Heraclitus restored the Holy Cross to Jerusalem, after defeating the Persians who had stolen it.
Christians “exalt” (raise on high) the Cross of Christ as the instrument of our salvation. Adoration of the Cross is, thus, adoration of Jesus Christ, the God Man, who suffered and died on this Roman instrument of torture for our redemption from sin and death. The cross represents the One Sacrifice by which Jesus, obedient even unto death, accomplished our salvation. The cross is a symbolic summary of the Passion, Crucifixion and Resurrection of Christ — all in one image.
The Cross — because of what it represents — is the most potent and universal symbol of the Christian faith. It has inspired both liturgical and private devotions: for example, the Sign of the Cross, which is an invocation of the Holy Trinity; the “little” Sign of the Cross on head, lips and heart at the reading of the Gospel; praying the Stations (or Way) of the Cross; and the Veneration of the Cross by the faithful on Good Friday by kissing the feet of the image of Our Savior crucified.
above taken from: http://www.wf-f.org/ExaltCross.html