According to The Manual on the Liturgy of the Lutheran Book of Worship by Philip Pfatteicher and Carlos Messerli, the celebration of Holy Cross Day dates from 335 A.D. when a basilica built by Constantine in Jerusalem was dedicated. This feast day has enjoyed wide popularity in both Eastern and Western Christianity throughout the centuries since that time. The cross is a well known symbol in our culture.
People wear crosses on chains around their necks.
The sign of the cross is made by most Christians in the practice of their personal and corporate piety. And the cross stands in a prominent location in nearly every church as a symbol of the Christian faith. In and of itself, however, the cross means nothing at all. For those who do not know the Christian story, the cross might be nothing more than a convenient pole for stringing telephone wires through the countryside, a rack for drying clothes, or a diagram on a street sign before an intersection. But for those who know the story, the cross is a powerful symbol of God's love in Jesus Christ which offers a sinful world eternal salvation.