What survives is a cropmark, a faint outline where stunted, slightly different growth betrays the ghost of a levelled earthwork beneath. Walk the field at the right moment and you can trace a roughly circular area of around 40 metres in diameter, the last legible signature of a rath that has otherwise been erased from the landscape.

A rath is an early medieval enclosure, typically formed by one or more earthen banks and ditches, used as a farmstead or residence. The one at Larganboy was broadly oval in plan, measuring approximately 40 metres on its north-west to south-east axis and 35 metres across, and it sat on a low, naturally domed rise in the ground, a position that would have given its occupants a modest but useful elevation over the surrounding land. Intriguingly, the site does not appear on the first Ordnance Survey six-inch map of 1838, which suggests it may already have been substantially degraded by that point, or simply overlooked. It does appear on the later 25-inch plan and on the 1917 six-inch revision, where a curving field boundary along the southern arc hints at what may have been the outer edge of a fosse, the ditch that typically accompanied a bank enclosure of this type. By the time an inspection took place in 1998, the bank had been fully levelled, leaving only the cropmark as evidence of the original circuit.