The Rock of Cashel has been a fortress or a religious site for thousands of years. The oldest building still standing is the round tower which is about 900 years old. It is also called Cashel of the Kings and St. Patrick's Rock. I also photographed the Rock of Cashel in January 2004.
The Heritage Ireland web page for the Rock of Cashel says: http://www.heritageireland.ie/en/South-East/RockofCashel/A spectacular group of Medieval buildings set on an outcrop of limestone in the Golden Vale including the 12th century round tower, High Cross and Romanesque Chapel, 13th century Gothic cathedral, 15th century Castle and the restored Hall of the Vicars Choral. Attractions include an audio-visual show and exhibitions. Access for visitors with disabilities by prior arrangement.
Next photo of the Rock of Cashel.
The Catholic Encyclopedia at http://www.newadvent.org/cathen/11554a.htm says:St. Patrick next proceeded to Munster. As usual, his efforts were directed to combat error in the chief centres of authority, knowing well that, in the paths of conversion, the kings and chieftains would soon be followed by their subjects. At "Cashel of the Kings" he was received with great enthusiasm, the chiefs and Brehons and people welcoming him with joyous acclaim. While engaged in the baptism of the royal prince Aengus, son of the King of Munster, the saint, leaning on his crosier, pierced with its sharp point the prince's foot. Aengus bore the pain unmoved. When St. Patrick, at the close of the ceremony, saw the blood flow, and asked him why he had been silent, he replied, with genuine heroism, that he thought it might be part of the ceremony, a penalty for the joyous blessings of the Faith that were imparted. The saint admired his heroism, and, taking the chieftain's shield, inscribed on it a cross with the same point of the crozier, and promised that that shield would be the signal of countless spiritual and temporal triumphs.