The Celtic Cross, or Ionic cross, has it's roots in a pre-Christian variation of the Solar Cross. Examples of the Celtic cross date back as far as 5000 years BCE. It's origins are not known, but it was known to be an early symbol of the sun god Taranis. In Ireland, it is a popular myth that the Celtic Christian cross was introduced by St. Patrick during his time converting the pagan Irish. It is believed that St. Patrick combined the symbol of Christianity with the sun cross, to give pagan followers an idea of the importance of the cross by linking it with the idea of the life-giving properties of the sun. In Celtic regions of Ireland and later in Great Britain, many free-standing upright crosses (or high crosses) were erected by Irish monks, beginning at least as early as the seventh century. Some of these 'Celtic' crosses bear inscriptions in runes. There are surviving free-standing crosses in Ireland today.
The most famous standing crosses are the Cross of Kells, County Meath, Ireland; Ardboe Auld Cross, Ardboe, County Tyrone; Cross of the Scriptures, Clonmacnoise, Ireland; and more. The Celtic Revival of the mid-19th century led to an increased use and creation of Celtic crosses in Ireland, and stimulated interest in the Christian and non-Christian Celtic crosses as a symbol for a renewed sense of heritage within Ireland. Today the Celtic cross continues its rich history in Ireland.