Celtic cross

The Celtic cross is one of the best known Irish symbols and although it is tightly associated with Christianity today, the Celtic cross pre-dates Christianity.
The history of this symbol is not clear.There are many interpretations and legends about its original meaning.
In pagan times, this cross was a symbol of fertility and life.Some suggest that the Celtic cross is derived from the Chi Rho symbol popularized by the Christian Roman emperor Constantine.
No one is certain about where the distinctive circle of the Celtic cross came from or what it means. Among some ancient peoples, a circle was used to represent the moon, and a circle with a cross symbolized the sun.

The Cross did not become a common symbol of Christianity until the 4th century, signifying the unity of heaven and earth.

There is a popular legend in Ireland that the Celtic Catholic cross was introduced by Saint Patrick and others responsible for Ireland's conversion to Christianity using symbols familiar to the Irish in order to make transition easier.
Whatever the real history is, there is no doubt of its mystery and extraordinary beauty.