It reads, at first glance, as an unremarkable ring of low banks and a silted ditch, the kind of earthwork that turns up in every Irish townland. But this one, known as Site M in the Knowth complex, turns out to be something considerably more layered: a monument that grew outward over several centuries, combining a burial ground and a metalworking area in ways that do not fit neatly into the usual categories of early medieval site.

Seasonal excavations carried out between 2002 and 2004 found that the visible outer earthworks, which form a roughly circular enclosure about 105 metres across with an inner bank, a fosse, and an external bank, enclose two earlier sub-circular ditches whose origins go back to the sixth century AD. The innermost of these ditches, radiocarbon-dated to between 573 and 658 cal. AD, surrounded a burial ground where 52 graves were uncovered, most of them shallow and unmarked, orientated west to east with the head placed west, as was standard Christian practice. Ten slab-lined graves were found along the southern edge. Adults and juveniles were both present, though the remains were in poor condition and only nine of the adults could be sexed with confidence. In the middle enclosure, which appears to have been dug around 662 to 805 cal. AD, there were no burials but clear evidence of metalworking: heat-shattered stones, burnt clay fragments, and charcoal-rich soils over a cobbled surface, suggesting a workshop of some kind, though no furnaces survived. The radiocarbon dates point to a monument that expanded outward over roughly three centuries, from the innermost ditch around 600 AD to the outer banks, which may date to the ninth or tenth century. Among the finds recovered were a gilt bronze Anglo-Saxon mount, a blue glass bead, a bronze baluster-headed ring-pin, a Hiberno-Norse strap end, and, most unexpectedly, a sperm whale's tooth. That last object implies connections reaching well beyond the inland plains of Meath. The separation of burial from craft activity within the same enclosed complex has led researchers to consider the possibility that this was a secular cemetery rather than an ecclesiastical one, though the question remains open.