It was an inauguration site of the Dalcassians and it is likely to be where Brian Boru himself assumed his leadership in 976 upon his brothers death. It is located near Tulla in Co. Clare. Voices from teh Dawn has some brilliant information on it here. https://voicesfromthedawn.com/magh-adhair/ It must be 15 years or so since I last visited and I'm well overdue a revisit. There is a bullaun stone located near the mound and a standing stone on the other side of a river that runs near it. I had this picture on an external hard-drive that broke down on me. Thankfully I was able to have all the photos recovered, so The Tipperary Antiquarian's archive remains intact. (Including all the early out of focus ones from the early 2000s like this one!)
My blog looks at the archaeology and heritage of sites in Tipperary and surrounding areas. As many of these sites are on private property, it is important to request permission from the landowner before entering private lands so that access does not become a problem across all sites.