Newgrange is a large circular mound with a stone passageway and chambers inside. The mound has a retaining wall at the front and is ringed by 'kerbstones' engraved with artwork. There is no agreement about what the site was used for, but it has been speculated that it had religious significance – it is aligned with the rising sun and its light floods the chamber on the winter solstice. It is the most famous monument within the Neolithic Brú na Bóinne complex, alongside the similar passage tomb mounds of Knowth and Dowth, and as such is a part of the Brú na Bóinne UNESCO World Heritage Site. Newgrange also shares many similarities with other Neolithic constructions in Western Europe, such as Maeshowe in Orkney, Scotland and the Bryn Celli Ddu in Wales.