Loughcrew
Loughcrew is a megalithic cemetery containing around thirty passage tombs spread across four hills. They date to 3000 BC, contemporary with Newgrange (3200 BC). The most famous is Cairn T, which measures about 35 metres in diameter and is surrounded by kerbstones. At the March and September equinoxes, a beam of sunlight from the rising sun enters the passage and slowly illuminates the decorated backstone at the rear of the chamber. As the sun rises, the light moves across the carved surface, revealing the patterns. Rayed circles are the signature carving at Loughcrew - distinct from the spirals at Newgrange and the concentric rectangles at Knowth.