Newgrange is best known for the illumination of its passage and chamber by the rising sun at the Winter Solstice. Above the entrance to the passage of the mound there is an opening called a roof-box. On mornings around the winter solstice a beam of light penetrates the roof-box and travels up the 19 meter passage and into the chamber. As the sun rises higher, the beam widens so that the whole chamber is dramatically illuminated.