The execution of Kerbstone 52 is as accomplished and complex as the Entrance Stone, and may well have been carved by the same artist. The stone chosen to be engraved was divided in two by a broad channel which runs down the centre. Kerbstone 52 has a distinctly bovine feel to it, which makes sense in the context of the Newgrange mythology: Boann, the goddess of the river Boyne is a cow deity.
The artwork is quite alien and beautiful. On the right side of the stone, a complex essay on the number three takes place, in a design that seems quite alien in the catalogue of engraved symbols which would be quite at home on a Mesoamerican pyramid.
Along with the Entrance Stone, Kerbstone 52 divides the mound in two along an southeast to northwest axis and faces the summer solstice sunset, an alignment also found at Cairn G in Carrowkeel and Shee Lugh on the ridge of Moytura.
At some stage before the great mound was added, you could have stood here and looked over the stone, across the site of the chamber, and down the passageway: in other words, during the 'setting out' and surveying of Newgrange, the primary solstice alignment was marked on the two main kerb-stones.
The three groups of three have always reminded me of plug sockets, and this may make sense in the context of Leylines or energy lines. Michael Poynder in his book, Pi in the Sky, talks about a large energy line crossing Ireland from Knocknarea to Newgrange, and believes that these three symbols represent the three strands of the line.
The left side has a set of 14 lozanges on the lower portion, with a set of spirals above. Poynder believes that the lozanges are a symbol or unit of length, showing the distance to Queen Maeve's Cairn on the west coast.
Some researchers hope that a second undiscovered passage may remain hidden behind Kerbstone 52, though investigations by archaeologists late in 2011 failed to find anything.
However, given that the mound bulges somewhat at this point, there may be an earlier, smaller mound here which was incorporated into the great mound. This seems likely, as a building of this size and complexity would have been developed in phases.
There is some evidence that the huge mounds of both Knowth and Dowth were built over smaller mounds, and that stones from both Newgrange and Knowth were recycled from older buildings.