To this day the Eastern Churches, Catholic and Orthodox alike, celebrate the Exaltation of the Holy Cross on the September anniversary of the basilica's dedication. The feast entered the Western calendar in the seventh century after Emperor Heraclius recovered the cross from the Persians, who had carried it off in 614, 15 years earlier. According to the story, the emperor intended to carry the cross back into Jerusalem himself, but was unable to move forward until he took off his imperial garb and became a barefoot pilgrim.
Comment:
The cross is today the universal image of Christian belief. Countless generations of artists have turned it into a thing of beauty to be carried in procession or worn as jewelry. To the eyes of the first Christians, it had no beauty. It stood outside too many city walls, decorated only with decaying corpses, as a threat to anyone who defied Rome's authority—including Christians who refused sacrifice to Roman gods. Although believers spoke of the cross as the instrument of salvation, it seldom appeared in Christian art unless disguised as an anchor or the Chi-Rho until after Constantine's edict of toleration.
Source: http://www.americancatholic.org