For most of the year it is simply a field. It is only under the right agricultural conditions that this patch of ground gives itself away.

What the plough reveals is a burnt mound, a type of prehistoric site found widely across Ireland and Britain. The term refers to an accumulation of fire-shattered stone that built up, often over repeated use, around a trough or pit where water was heated by dropping stones that had been made red-hot in a fire. The purpose is debated, with suggestions ranging from cooking to bathing to industrial processes, but the basic method is well understood. The presence of an old stream bed adjacent to this site fits the pattern closely, since a reliable water source was essential to the process. What makes the Longgraigue site particularly interesting is its context: another burnt mound lies approximately sixty metres to the west, and a third is about eighty metres to the north-north-east. Three such sites clustered within a short distance of one another, all near the same valley head, suggests that this landscape was returned to repeatedly, and that the water source or the location itself held some practical or perhaps social significance over time.