Watch: A modern miracle at Fourknocks – the sun illuminates ancient art

In June, during a visit to the Neolithic passage-tomb of Fourknocks in Co. Meath, I was witness to a beautiful phenomenon that resulted from a combination of modern architecture and ancient art. Megalithic art – engravings made upon stone by humans around 5,000 years ago – was being illuminated by a pulsating beam of the summer sun, emerging through a narrow slit in the roof.

This phenomenon was not a part of the ancient integral design of the monument. Rather, it was the result of some clever modern thinking which, in addition to protecting the prehistoric art, was also allowing (accidentally) its striking illumination.

It was a windy day outside and strong summer sunshine was being interrupted with a flow of fast-moving cumulus clouds. The result was that the light was shimmering in a most beautiful and extraordinary fashion.

I had visited Fourknocks dozens of times over the past 20 years and never witnessed this phenomenon. After its excavation in the early 1950s, Fourknocks was left with no roof, because it was thought the original roof was made out of wood. This meant the art on its stones was exposed to the elements – wind and rain and frost.

Sunlight enters through an aperture in the roof and illuminates ancient chevrons.


A new roof was made for the monument some time after that by the Board of Works with advice from the archaeologists. This domed concrete addition might have left the place in darkness were it not for the clever inclusion of several slits or apertures to admit light. The result is that there is sufficient light inside the monument to prevent the need for electrical lighting.

Some of these apertures are above the stones which contain megalithic art. These can be viewed in comfort (and awe) as a result of the design of the dome.

I was not the first to notice this beautiful occurrence. In the late 1970s, author and artist Martin Brennan describes a similar encounter with this wonderful phenomenon in his book The Boyne Valley Vision, published in 1980:

I was busy taking sitings of the horizon from the interior in the fashion of the Mayan astronomers: that is, taking bearings using the two portal stones at the entrance... My attention was called to an interesting phenomenon. Through the aperture a strong light beam was striking the stone at the corner of the chamber and the entrance passage. I stared in amazement. The chevron markings on the stone were effectively registering the movement of the sun across the sky. Unwittingly, the Board of Works had constructed a Neolithic scientific instrument for charting the sun's movements. If the aperture were placed in the right position and made smaller, this stone could act as a timepiece, an effective graph for charting not only the movements of the sun but, under the right conditions, the movements of the moon.

Illuminated art ... zigzags from 5,000 years ago lit by a beam of glimmering sunlight.


I watched, as Brennan had done years before, a beautiful, dazzling light show – this one made all the more impressive by the pulsating, flickering light of the strong summer sun beam as the clouds passed in front of it. Brennan was clearly impressed:

The shaft of light was surprisingly strong and strikingly beautiful. It was the laser effect: the same effect that is achieved at Newgrange on winter solstice.

Having witnessed the spectacle at Fourknocks while inside the monument with a group of visitors, I decided to return the next day with my camera equipment to record it. I'm so glad I did. The result is the beautiful video (embedded above). 

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This page was last updated on 26th August 2019 @ 1:53 PM