Newgrange, a prehistoric tomb in Ireland

(gentle music) - [Steven] We're in the Boyne Valley in Ireland. This area is home to one of the largest collections of neolithic and megalithic art and culture that exists anywhere in the world. - [Lauren] We've just left Newgrange, part of the Bru na Boinne complex and while Newgrange is not the largest of the tombs that we just visited, it is one that you can still go inside of. - [Steven] And you enter along an axis that is, like Stonehenge, built later, aligned with the winter solstice, which is to say the day of the year when the day is shortest. - [Lauren] And Newgrange was built sometime around 3,200 BCE, but it took a while to build. By some estimates, it took more than 70 years to construct. - [Steven] In order to enter the tomb, you walk around two stones, one that is vertical and one that is horizontal that has been carved with a triple spiral motif. And on the winter solstice, the shadow cast by the standing stone is drawn across the horizontal stone and it's behind these stones that one can enter into the tomb structure itself. There is a long, low passage. I had to duck and you have to squeeze between enormous stones that are set upright to get into the center of the structure. - [Lauren] There are several nodes. It creates a cruciform or a cross shape, and in each of those small chambers, there are enormous basin stones. And in the rightmost chamber, you have elaborate decoration on the surface of the ceiling. - [Steven] And in the center cruciform space, there is a higher ceiling and this is held up by a corbel arch, that is, by large stones that extend further and further towards the center as they move upward and that are held in place by counterweights, that is, by the mass of loose stone and soil that exists above that. - [Lauren] And it was made without mortar which is remarkable considering not a single drop of water has made it inside this passage tomb. We are in Ireland where it rains all the time. Part of the reason for that is that above the passage tomb, we have a great amount of earth and loose stones that were packed on top to protect the tomb but also to make it rise up from the earth. - [Steven] But it's not just modern day visitors that enter into this tomb. On the winter solstice, the sun is so perfectly aligned that a beam of light enters above the doorway through a secondary window into the tomb and makes it along the floor just to the backmost chamber. - [Lauren] For 17 minutes on the winter solstice, that light is visible and prominent inside that passage tomb. - [Steven] These are so old that there are no written records. We can only look at the physical evidence that exists and try to understand how these were used. - [Lauren] The remains of five people were found inside the tomb, three that were cremated, and two that had been left alone. And so we know that this was used as a burial place. But given the immense amount of of time and energy and effort to construct these tombs, archeologists and art historians and others have wondered if maybe there were other uses for this because of that solar alignment. - [Steven] There are three distinct types of stone that make up these tombs. There is a black granite, which comes from a distant mountain range. There's bright white quartz stone and then there were very large limestone kerbs. - [Lauren] When this tomb was excavated and put back together, because part of it had fallen apart, they found many of these white quartz stones and black granite at the exterior. The people who built Newgrange clearly had an interest in the color differences of those stones. And it creates this interesting contrast that sets off the entrance. - [Steven] We're surrounded by more neolithic carving that exists anywhere else in Western Europe and there's a perfusion of different kinds of relief carvings on these large limestone kerb stones. There are chevrons, that is, zigzags, spirals, two triple spirals, and archeologists suspect that they had more specific meaning. We just don't know what those meanings are. - [Lauren] What we do know is that these massive stones, many of them decorated, lined the base of the tomb all the way around the exterior, which means that people had to locate the stones from far away, bring them here, most likely via the Boyne River. They had to then place them around the tomb and then they had to carve. - [Steven] But we need to be cautious because these tombs have been used and occupied and they have been entered over and over again for a very long time. In the 20th century, there have been efforts to shore up these structures and to conserve them, but that intervention is evident and can be seen most obviously in the concrete shelf That helps protect the carved kerb stones that surround the structures. - [Lauren] And that's most evident at Knowth where you see not only that lip that you mentioned, but you can see evidence of structures that were built on top of the mound. These places, even if people were unaware of what was inside of these large mounds, they continue to be where people were engaging with this land. (gentle music)