Newgrange (Irish: Sí an Bhrú) is a prehistoric monument in County Meath in Ireland, located on a rise overlooking the River Boyne, 8 kilometres (5.0 mi) west of Drogheda. It is an exceptionally grand passage tomb built during the Neolithic Period, around 3200 BC, making it older than Stonehenge and the Egyptian pyramids. It is aligned on the winter solstice sunrise. Newgrange is the main monument in the Brú na Bóinne complex, a World Heritage Site that also includes the passage tombs of Knowth and Dowth, as well as other henges, burial mounds and standing stones.

Newgrange consists of a large circular mound with an inner stone passageway and cruciform chamber. Burnt and unburnt human bones, and possible grave goods or votive offerings, were found in this chamber. The mound has a retaining wall at the front, made mostly of white quartz cobblestones, and it is ringed by engraved kerbstones. Many of the larger stones of Newgrange are covered in megalithic art. The mound is also ringed by a stone circle. Some of the material that makes up the monument came from as far as the Mournes and Wicklow Mountains. There is no agreement about its purpose, but it is believed it had religious significance. It is aligned so that the rising sun on the winter solstice shines through a 'roofbox' above the entrance and floods the inner chamber. Several other passage tombs in Ireland are aligned with solstices and equinoxes, and Cairn G at Carrowkeel has a similar 'roofbox'. Newgrange shares similarities with some other Neolithic monuments in Western Europe; especially Gavrinis in Brittany, which has a similar preserved facing and large carved stones, Maeshowe in Orkney, with its large corbelled chamber, and Bryn Celli Ddu in Wales.

Its initial period of use lasted about 1,000 years. Newgrange then gradually became a ruin, although the area continued to be a site of ritual activity. It featured in Irish mythology and folklore, in which it is said to be a dwelling of the deities, particularly The Dagda and his son Aengus. Antiquarians first began its study in the seventeenth century, and archaeological excavations began in the twentieth century. Archaeologist Michael J. O'Kelly led the most extensive of these from 1962 to 1975 and also reconstructed the front of the monument, a reconstruction that is controversial and disputed. This included an inward-curving dark stone wall to ease visitor access. Newgrange is a popular tourist site and, according to archaeologist Colin Renfrew, is "unhesitatingly regarded by the prehistorian as the great national monument of Ireland" and as one of the most important megalithic structures in Europe.