Newgrange, one of three passage tombs in Bru na Boinne, was built over 5,000 years ago. The tomb is exactly positioned so that at dawn on Winter Solstice, a shaft of light penetrates the passageway and illuminates the inner chamber. The passage to the center of the tomb is about 20 meters long, the inner chamber is about 5 metres deep / 6.5 meters wide, and the ceiling of this inner chamber is spiraled upward using huge stones that were stacked in a corbeled roof pattern, about 6 meters high. Inside are many etchings, the most significant of which is the tri-spiral design, which you can see here on the entrance stone. Nobody knows exactly what these designs meant to the original artists, why the tomb itself was constructed, and how it was so carefully aligned with the solstice.