The entrance to Newgrange

21 Newgrange mound should be properly referred to as a cairn, because it consists of water-rolled pebbles, each of which is between 6 to 9 inches across.

22 The entire mound contains an estimated 200,000 tonnes of material, and it has been estimated construction would have taken about 30 years using a workforce of about 300.

23 It is not known with any certainty how the larger stones which form the kerb and passage and chamber of Newgrange were brought to the site. Many of these stone slabs, 550 in number, were collected from where they had been lying in the landscape. Because many of the stones were found to be weathered, it is believed they were not quarried, so there would have been a huge logistical task in finding suitable boulders dotted throughout the landscape.

24 Because Newgrange sits atop a ridge, many of the large slabs would have needed to be brought uphill, again suggesting a highly organised community was behind its construction.

25 Michael J. O'Kelly, who excavated Newgrange, felt that the workforce involved in building Newgrange would have been divided up into about six gangs or teams, each with its own set of tasks and area of expertise.

Newgrange and standing stones

26 There is no doubt that the people in charge of Newgrange's construction, from the master builder and architect down to the team foremen, were "intelligent and experienced", according to O'Kelly.

27 The passage and chamber orthostats would have been put in place before construction of the cairn itself actually began, and it is probable the kerb would have been marked out at this stage too.

28 The addition of grooves onto the top surface of the passage roof stones shows that the builders were aware of the need to redirect water seepage from the cairn, and therefore keep the passage water-proofed.

29 It is known that the white quartz, which was found on the ground in front of Newgrange during excavations, was not originally placed there by the builders. Some of the kerbstones which had fallen forward some time after the construction of the monument were found to be directly in contact with the subsoil, with no quartz beneath them.

30 Various estimates of the original height of Newgrange have been guessed at in recent centuries, with some explorers of the site giving estimates as high as 45.7 metres (150 feet). Archaeologists believe the actual height would not have been much more than 11 to 13 metres.