Dowth () is the site of Neolithic passage tombs near the River Boyne in County Meath, Ireland. It is one of the three main tombs of the Brú na Bóinne World Heritage Site, along with Newgrange and Knowth. Its features align it with the other passage tombs, which date from around 3200 BC. Unlike its bigger neighbours, Dowth has mostly been left as a ruin, although its smaller inner chambers are largely intact. The Royal Irish Academy carried out a botched excavation in 1847, leaving a large crater in the mound that has never been repaired. with a lintelled (not corbelled as in Newgrange or Knowth) roof. Dowth South is 3.5 metres long and ends in a roughly circular chamber with a modern concrete roof (the original roof having collapsed). This may be the earliest part of the tomb, later brought within the design of the cruciform tomb. This annex is floored with a 2.4 metre-long flagstone containing an oval bullaun (artificial depression). Until recently, the cruciform tomb was reached by climbing down a ladder in an iron cage, and crawling about over loose stones. Now, access is restricted, and all the features are guarded by metal grilles.

A kerbstone with cup-marks, a spiral, and a flower-like design marks the entrance to Dowth South. While the current roof is modern, it is possible the original one was corbelled, as at Newgrange.

The mound originally had about 115 kerbstones surrounding it. Kerbstone 51, sometimes called the Stone of the Seven Suns, features a number of radial circular carvings, This large crater has still not been repaired. In 1970, archaeologist Peter Harbison dated the tomb at 25002000 BC.

Archaeological and geophysical field surveys of the entire site, including later monuments, were carried out episodically from 2012 to 2015. In July 2018, another passage tomb in the grounds of nearby Dowth Hall was excavated, revealing significant examples of Neolithic rock art similar to those at Dowth and the other Brú na Bóinne sites.

Astronomical alignment

Like its better known neighbour Newgrange, the monument has a significant astronomical alignment. In The Stars and the Stones: Ancient Art and Astronomy in Ireland, Martin Brennan (19422023, an Irish-American author and artist) records a remarkable alignment. From November to February, the rays of the evening sun reach into the passage and then the chamber of Dowth South. Brennan reports that, during the winter solstice, the light of the low sun moves along the left side of the passage, then into the circular chamber, where three stones are lit up by its rays. The convex central stone reflects the sunlight in to a dark recess, illuminating the decorated stones there. This tale has been linked with solstice alignments at Brú na Bóinne. It has also been linked with DNA analysis in 2020, which found that a man buried at nearby Newgrange had parents who were most likely siblings. This could mean that knowledge of the events survived for thousands of years before being recorded as a myth in the Middle Ages.

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  • World Heritage information about Knowth
  • Brú na Bóinne – Newgrange, Knowth and Dowth (Meath County Council)
  • (Midwinter sunset in modern times. Due to the change in the obliquity of the ecliptic, the position of sunrise and sunset on the horizon has shifted by one degree since Neolithic times, so the precise horizontal illumination no longer occurs. (see ).)