The ring barrow at Balgarrett in County Westmeath was laid out on a narrow esker, a long sinuous ridge of gravel and sand deposited by meltwater beneath an ice sheet during the last glaciation, and the choice of that particular elevated spine seems to have been very much intentional. The result is a monument that behaves differently on each side, its geometry shaped as much by the rising ground beneath it as by the hands that built it.

A ring barrow is a roughly circular burial monument consisting of a central mound enclosed by a ditch and an outer bank. At Balgarrett, the central mound measures approximately ten metres by eight point eight metres, with the whole monument spanning around twenty-one and a half metres northeast to southwest. Because the esker rises towards the southwest, the mound's apex sits considerably higher above the ditch on the northeast side, by about one point four five metres, than on the southwest, where the figure drops to just thirty-four centimetres. The outer bank compensates in the opposite direction: it is at its most substantial on the southwest, rising half a metre above the ditch and stretching up to five metres in width, while on the northeast it shrinks to something closer to a low step. On the northwest and southeast flanks, where the ground drops away steeply on both sides of the esker, the bank is barely detectable at all. When surveyor David McGuinness examined the site in 2013, the high grass made it difficult to trace the outer edge of the bank precisely, so the overall dimensions should be understood as careful approximations rather than exact figures. Frewin Hill is visible to the northeast, and the view northward is described as considerable. The barrow sits within a deliberately unplanted clearing inside commercial forestry, and four further barrows lie within the same townland, the nearest roughly five hundred metres to the east-southeast.