At the base of the Hill to the east, in the townland of Rathcarran, lies a large, Boyne-type embanked enclosure (previously unidentified, now assigned the SMR No. ME030-035—-). This is very similar to monuments of this type in Brú na Bóinne: c. 160m in diameter with very low banks (in this case no more than 1m), sloping downward slightly to the northwest and with a slight dome centrally, characteristic of interior scarping from which the enclosing bank was created. This is considerably further west than other Meath examples of this site type, and, assuming it is a late-Neolithic feature (as we assume these embanked enclosures are), implies significant earlier prehistoric activity in the area.
One obvious place for such activity would be the hilltop itself. To the west of the road lies what appears to be a significant cairn (clearly visible in the field). Earthworks in this western field also appear to be suggested by early aerial photography. A second potential cairn feature lies within Tlachtga itself and comprises all or part of the central portion of the monument.
Between the hilltop and the embanked enclosure lies a low ridge, marked in the GSI Quaternary dataset as an esker, although of peculiarly linear form. This ridge also includes three possible mounds, the southernmost on top of a low hill. It is hoped that these will be the subject of future rounds of geophysical survey.