³Herity, Michael. Irish Passage Graves: Neolithic Tomb-builders in Ireland and Britain, 2500 B.C. New York: Barnes & Noble, 1975. 3.
The 1847-48 excavation report estimated the effort required: "When perfect, the cubical content of the whole may be estimated at about 75,000 Cubic Yards, & considering the probable means then available for performing such work, 6 men would be required to collect & place the materials of each Cubic Yard in a day, so that the formation of the Mound itself, without any reference to internal Chambers, would require the labour of nearly half a million of men for a day, when we consider the remote period at which this must have been executed, the limited number of men which could then have been procured for the purpose, the great difficulty of transporting such bulky materials to a distance as those stones surmounting the bank composing the chambers of the Mound, & the consequent great length of time which must have been consumed in the creation of the work, even this apparently rude structure will bear a favourable comparison with some of the more celebrated works of modem times." (O'Kelly, M.J., Claire O'Kelly, V.R. O'Sullivan, and R.H. Frith. "The Tumulus of Dowth, County Meath." Proceedings of the Royal Irish Academy 83C (1983): 1586-88.)