¹Hall, S. C., and S. C. Hall. Ireland, Its Scenery, Character, etc. Vol. 3. London: How and Parsons, 1841. 260.

²Condit, Tom, and Brian Lacy. The Beltany Stone Circle. Bray: Archaeology Ireland. Heritage Guide No. 4 (1998).
Only Lough Gur's Grange Stone Circle is larger; 46m v. 45m in diameter.
While most sources count 64 stones in the circle, a 1988 journal article refers to 65 stones. (Van Hoek, M.A.M. "The Prehistoric Rock Art of Co. Donegal (Part II)." Ulster Journal of Archaeology Third 51 (1988): 25.)
While most of the stone circles in Ireland are thought to have been constructed from c. 2100 BCE to 700 BCE, new data indicates that the Beltany Stone Circle may have been constructed as early as 3,000 BCE. See the reference to the “Rediscovering an Ancient Landscape" conference in Raphoe.

³Beltany is actually the name of the townland to the SW; the stone circle is found in Tops townland.

⁴ La Bealtaine is a "cross quarter day," halfway between the Spring Equinox and the Summer Solstice.

⁵Grinsell, Leslie V. Folklore of Prehistoric Sites in Britain. Newton Abbot: David & Charles, 1976. 18.
According To Stuart Piggott, "It is also possible that the association of the far more ancient stone circle with the more familiar and more recent Celtic calendar ritual was a way for the Elizabethan English to subjugate something wild, something that represented a darker unknown: that of the “frontier antagonist.” As Margaret Hodgen wrote, “…the epithets used to describe the folk on Britain’s Celtic border were interchangeable with those applied to the Negroes in Africa or to the Indians across the Atlantic. While sovereigns of the realm were struggling to pacify the tribal Celts, and the Puritan colonists in North America were wrestling with the Red Indian for his soul and his land, all frontier antagonists looked more or less alike.” (Piggott, Stuart. Ruins in a Landscape: Essays in Antiquarianism. Edinburgh: UP, 1976. 65.)

⁶Condit.
According to a blog post here, the Milesian warrior Itha "was buried in the highest point in this area so that even in death people would still have to raise their heads to look at him. His tomb is known as the Foyde."

⁷Condit.

⁸"Summary Descriptions of Passage Tombs in County Donegal." Archaeology Ireland. Web. 04 Feb. 2016.<http://www.archaeology.ie/sites/default/files/media/publications/smi-vol-6-text-and-plates-part-9.pdf>.
Fagan, Thomas. OS Hill Drawing Antiquity Books, Co. Donegal. 1845-48. MS. National Archives, Dublin, n.p.

⁹Van Hoek, M.A.M. "The Prehistoric Rock Art of Co. Donegal (Part II)." Ulster Journal of Archaeology Third 51 (1988): 25.

¹⁰Whitaker, Alex. "Beltany" Ancient Wisdom. Web. 04 Feb. 2016. <http://www.ancient-wisdom.com/irelandbeltany.htm>.
"Bealtaine was one of the four major festivals of ancient Ireland and marked the beginning of summer, the other festivals were: Lugnasadh, which was celebrated at the start of August and marked the beginning of Autumn); Samhain (the origin of today’s Halloween) marked the beginning of Winter; and Imbolc which was normally celebrated in early February and marked the beginning of Spring." (http://timetravelireland.blogspot.com/2013/10/beltany-stone-circle-county-donegal.html)

¹¹Battersby, Eileen. "In Beltany's Inner Circle." The Irish Times [Dublin] 5 Nov. 2005: Web. <http://www.irishtimes.com/news/in-beltany-s-inner-circle-1.514554>.

¹²A replica of the Beltany Stone Head is in the Donegal County Museum in Letterkenny. Dating of the idol was posited from stylistic inferences, particularly from its neck-ring (a torc, or possibly a tattoo).

¹³Rynne, Etenne. "The Three Stone Heads at Woodlands, near Raphoe, Co. Donegal." Journal of the Royal Society of Antiquaries of Ireland 94.2 (1964): 105-09.
According to the author, another stone head found nearby "is called 'Stumpy,' and... it was carved, during the last century, from a milestone which stood nearby, in the likeness of an unfortunate man who had had his two legs cut off."

¹⁴Rynne, Etenne. "Two Stone Axeheads Found near Beltany Stone Circle, Co. Donegal." Journal of the Royal Society of Antiquaries of Ireland 93.2 (1963): 193-96.
According to Rynne, while it is not possible to definitively connect the axeheads with the stone circle, they do provide evidence of trading contacts in Ireland 4000 years ago.

¹⁵Battersby.