Brú na Bóinne, Palace of the Boyne Mansion of the Boyne) is an area in County Meath, Ireland, located in a bend of theRiver Boyne. It contains one of the world's most important prehistoric landscapes, these 5,200 year old sites include the large Megalithic passage graves Knowth, Newgrange Dowth well as some 90 additional monuments. Newgrange is best known for the illumination of its passage and chamber by thewinter solstice. Above the entrance to the passage at Newgrange there is a opening called a roof-box, its purpose to allow sunlight to penetrate the chamber on the shortest days of the year, around December 21st, the winter solstice and at dawn, from December 19th to 23rd, a narrow beam of light penetrates the roof-box and reaches the floor of the chamber, gradually extending to the rear of the chamber.As the sun rises higher, the beam widens within the chamber so that the whole room becomes dramatically illuminated. The accuracy of Newgrange as a time-telling device is remarkable when one considers that it was built 500 years before the Great Pyramids and more than 1,000 years before Stonehenge.