Sí an Bhrú: Newgrange, marvel of Neolithic engineering

A few minutes after sunrise during the Winter Solstice sunlight illuminates the 63 foot long passage and chamber of the Neolithic passage tomb at Newgrange, County Meath, in Ireland. The lighting of the tomb lasts for some 17 minutes during which time the entire passage is lit, an event first observed in modern times by Professor Michael J. O’Kelly of University College, Cork, on 21 December, 1967. The annual occurrence is a testimony to the engineering skills of the Neolithic people who built it.

Newgrange was built circa 3200 BC, making it contemporaneous with Carnac and the less famous Stonehenge Cursus and predating the earliest phase of the Stonehenge monument by a century or so. It’s construction consists of a large mound covering over an acre of ground and rising to a height of 39 feet which is built of alternating layers of earth and stones. 97 kerbstones at the foot of the mound act as retainers. At the southeastern side of the mound an entrance provides access to the chambered passage which stretches for 63 feet into the mound and leads to a cruciform chamber with a corbelled roof.

Sketch of a cross section of the Newgrange passage grave made by William Frederick Wakeman, c. 1903

Above the entrance is an opening, called a roof box, which the builders aligned in such a way that a beam of light from the rising sun strikes the floor of passage at dawn on the shortest days of the year and as the sun continued to rise would illuminate the entire passage. It is a remarkable piece of precision engineering.

Lacking any historical record we may only speculate about the original purpose of Newgrange. Human remains, some of which were cremated, and grave goods have been discovered at the site suggesting that it was used as a tomb, while the later construction of timber circles near the mound reinforce the suggestion that Newgrange was a site of important ceremonial activity. The astronomical alignment at Newgrange, together with similarly observed alignments at other Irish Neolithic sites, may indicate that the builders placed significant importance on the sun in their system of belief. O’Kelly argued instead for a site that had a central place in a Neolithic ‘cult of the dead’. Medieval populations saw the mound as the home of the Dagda, High King of the Tuatha Dé Danann, or the burial ground of the ancient kings of Tara.

While we may now discountenance the different world view and traditions of the Medieval Irish, arguments may be made for both sun worship or a cult of the dead as the driving force behind the building of Newgrange. Nor are either mutually exclusive and it is possible that they were both elements within a belief system followed by the contemporary population. Without written records we can never be certain and can only make informed hypotheses based on available evidence.

What does seem evident is that the construction of Newgrange speaks of an organized and hierarchical society in which those in positions of power and influence were able to co-ordinate the activity of that society in a major collective endeavour. The lower estimate for construction of five years made by Professor Frank Mitchell seems unlikely given the sheer scale of the monument. O’Kelly’s estimate of a minimum of thirty years is more probable and if correct implies that construction took place during the life span of more than one generation of the builders. It is possible that those who envisaged Newgrange may not have lived to have seen its final construction.

This suggests the existence of an elite that was able to persuade the society it had influence over to contribute to building the mound over an extended period of time and to communicate its plans to successive generations. The construction itself which made use of large stone slabs, dressed drystone walls, a corbelled roof, and retaining walls to maintain the structural integrity of the mound, speaks of a society, and perhaps specialists within it, that possessed expert knowledge of the technological paradigm of their day. The precise alignment of the passageway and roof box further attest to the careful planning that went into construction, and the astronomical understanding that existed in the Neolithic population. The floor of the passage was constructed so that it rises gradually from the entrance to the innermost chamber where it is on a level with the roof box. In 3,200 BC this meant that light from the rising sun would strike the chamber at the break of dawn. This could only have been achieved through an understanding of the movement of the sun gained by careful and prolonged observation over a number of years.

Today among the thousands who enter, those lucky enough to win the fifty places available by lottery may experience the phenomenon of the winter solstice from inside Newgrange. I hope that as well as marvelling at the remarkable achievement of the builders that visitors keep a hopeful ear out for the strains of the Dagda’s harp which put the seasons in order whenever he played it. An apt association, however inaccurate, for the elaborate marking of the transition of one solar year to the next by the inhabitants of Neolithic Brú na Bóinne.

The Winter Solstice sun shines through the roof box at Newgrange