The Rock of Cashel in Tipperary County is said to have come from the devil himself. He was flying about with the rock in his mouth, was astonished to see St. Patrick, and dropped the huge stone. During a rebellion in 1580, an international brigade of Italian, Spanish and Basque soldiers landed in Ireland to help win back the country for Catholicism. They occupied the Dun An Oir Fort near Munster until they were defeated a few months later by English troops. Thousands of people make the pilgrimage to climb Croagh Patrick, the most sacred Irish mountain.
Ferries link Ireland with Brittany in France, which is also a Celtic region.
County Kerry was the first part of Europe sighted by Charles Lindbergh in his flight across the Atlantic. There are other crystal factories besides Waterford. Consider renting a boat and traveling down the River Shannon for a few days. St. Patrick's Day lasts a week in Ireland, the climax coming on 17 March. You can trace your Irish heritage at The Clare Heritage Centre.