Similar in size to both Newgrange and Knowth, this is the least investigated of the three major tombs. Unlike the other two monuments no conservation or restoration work has been carried out here. There are 66 visible kerbstones around half the circumference of the mound. There are two known tombs on the southwestern side of the mound and Dowth South appears to be aligned to the winter solstice sunset. There are suggestions that there may also be an undiscovered passage on the eastern side of the mound. There are hints of an early monastery at Dowth and there are a number of holy wells recorded in the area. There is documentary evidence indicating that the mound was converted into a motte castle in the late 12th century by the Anglo-Normans and a village was established close by.
Although it is possible to walk around the mound there is currently no access to either of the two tombs beneath the great mound. Further information may be obtained from the Brú na Bóinne Visitor Centre.