¹O'Brien, Matthew. "Fairy Forts." Personal interview. 1 July 1979.
It is interesting that Mr. O'Brien's comment about the legendary visibility of one "fairy fort" from another ("If you stand on one there, you can see two more all around you.") is corroborated by the research of Matthew Stout, who found that "The location of ringforts was such that the occupants of one ringfort would have been in visual contact with as many as seventeen of their neighbours." (Stout, Matthew. The Irish Ringfort. Dublin: Four Courts, 1997.19-20.)
Twenty years after we recorded the interview with Matty O'Brien we returned to visit with his family. Mr. O'Brien was deceased, but his grandchildren, who had never heard his voice, were eager to read his stories on our laptop. A photograph of this visit may be seen here. In 2012, a virtual O'Brien family reunion took place when links to the recordings were posted on Facebook.

²Stout, Matthew. The Irish Ringfort. Dublin: Four Courts, 1997. 53.
The author states that "there are 45,119 ringforts in Ireland of which 41% have been positively identified as of March 1995." Other terms for ringforts in Ireland include rath, lios (or lis), caiseal (or cashel), cathair (or caher or cahir) and dún (or doon). Rath and lios refer to an earthen ring-fort; caiseal and cathair a stone ring-fort. A dún was any stronghold of importance, which may or may not be ring-shaped.

³Stout 24.
The author states that "...the majority of Ireland's ringforts and crannogs were occupied and probably constructed during a three hundred year period from the beginning of the seventh-century to the end of the ninth-century AD." For his evidence he points out that the finds from ringforts usually include items that may be dated from the second half of the first millennium, such as certain pottery types (e.g. "souterrain ware") and ornamental beads and pins. The Garryduff bird is a beautiful example of a dateable find from a ringfort, c. 650 CE.

⁴Danaher, Kevin. Gentle Places and Simple Things: Irish Customs and Beliefs. Dublin: Mercier, 1964. 91-93.

⁵Stout 15.
The author cites information from 11 legal tracts revealing social hierarchies with "degrees of sub-division and complexity." (p. 110)

⁶Stout 11.
Stout explains, "Because the contemporary law tracts describe a king's principal dwelling to have been a uivallate ringfort, some notion is obtained of the lofty status of bivallate, and extremely rare trivallate, sites." (p. 18)

⁷Ní Cheallaigh, Máirín. "Going Astray in the Fort Field: Traditional' Attitudes Towards Ringforts in Nineteenth-Century Ireland." The Journal of Irish Archaeology, 15 (2006): 105
According to Matthew Stout, "Most excavated ringforts have revealed the foundations of a range of buildings within their banks indicated that the surviving monuments were in fact farmsteads which would have enclosed a single farming family and their retainers." ( Stout, Matthew. The Irish Ringfort. Dublin: Four Courts, 1997. 32.) Stout insists on the defensive capabilities of the ringforts by arguing that, "...none of these deficiencies, other than the absence of a palisade, seriously challenges the defensive nature of ringforts and it is unlikely that a population which worked on a daily basis with post and wattle fencing and housing would not have erected a similar structure along the tops of at least some of their enclosures." (pp. 19-20).

⁸Stout 13.

⁹Brenan, Samuel A. "Fairy Folk-Lore, Co. Antrim." The Journal of the Royal Historical and Archaeological Association of Ireland Fourth 9.78 (1889): 59.
It may be that the Tuatha Dé Danann symbolized the pre-Christian deities of the land. See Wikipedia article.

¹⁰Ní Cheallaigh 107-108.

¹¹Ní Cheallaigh 108.
The authors terms the overgrown fairy fort the "wild wood' of European folklore. She also asserts that some ringforts were used as cilleens, where the bodies of strangers and children who died before being baptized were buried.

¹²Evans-Wentz, W. Y. The Fairy-faith in Celtic Countries. London: H. Frowde, 1911. 32.

¹³Casey, Michael. "The Fairy's Chicken." Personal interview. 25 June 1979.

¹⁴Correll, Timothy C. "Believers, Sceptics, and Charlatans: Evidential Rhetoric, the Fairies, and Fairy Healers in Irish Oral Narrative and Belief." Folklore 116.1 (2005): 1.

¹⁵Ní Cheallaigh 107.
According to Ni Cheallaigh, "More than most other monuments of the Irish archaeological record, ringforts have lain at the intersection of diverging worlds of symbolic imaginings that encompass a wide variety of interacting social and cultural identities. These overlapping worlds have ranged from the cottages of the rural tenant labourer and farmer to the salons of the antiquarian elite and the excavation trench of the archaeologist. Engagement with the physical remains of ringforts was, and is, articulated through the social structures and belief systems of those who visited, actively avoided or, equally consciously, obliterated them."
The initial quotation is from Bourke, Angela. The Burning of Bridget Cleary: A True Story. New York: Viking, 2000. 48.

¹⁶Cray, Ed, and Francis D. Adams. "Fairy Rath." Western Folklore 17.4 (1958): 282.
Ultimately the government official for the Ministry of Lands (Erskine Childers) made the decision to "bend" the fence to avoid the fairy fort. (Stekert, Ellen. "Fairy Palace." Western Folklore 18.1 (1959): 50.)

¹⁷Harkin, Greg. "Sean Quinn's Downfall Is Fairies' Revenge Say Locals in Cavan." Irish Independent [Dublin] 22 Nov. 2011. Read online here.