Dowth together with Newgrange and Knowth are the three principal megalithic passage tombs
of the Brú na Bóinne World Heritage Site. The mound is 90 metres in diameter and 15 metres
high and surrounded by kerbstones, some of which are decorated.
The Samhain Sunrise in early November illuminates the chamber of the Mound of the Hostages on the Hill of Tara. Samhain is the cross quarter of the astronomical year, half way between the autumn equinox and the winter solstice.
Stonehenge on the Salisbury Plain in England is probably the best known and most studied megalithic structure anywhere in the world, yet its original purpose is still unclear. Even the celebrated summer solstice sunrise significance is in doubt, Stonehenge may actually have been built to mark the winter solstice sunset. The winter solstice would have been of much greater importance to the builders of Stonehenge, early farming communities who depended on the return of longer and warmer days to grow their crops.
The Beltany Stone Circle also called Beltany Tops is located close to Raphoe, Co. Donegal in the north west of Ireland. The Stone Circle was constructed about 2000 BC, it is about 44 meter in diameter. There are currently 64 stones, there may have orginally been up to 20 more stones.
Avebury is a large henge and stone circle surrounding the village of Avebury in the English county of Wiltshire. It was constructed about the same time as Newgrange and is one of the finest and largest Neolithic monuments in Europe.