The ringfort at Martinstown, a roughly circular enclosure of about twenty-three metres across, had been reduced to near-nothing, with only a single section of its bank still standing above ground at the south-west. What aerial photography revealed was the ghost of something that had once been quite deliberate and solid: a bank four metres wide and up to one and a half metres high, fronted by a wide external fosse, the term for the ditch dug to create the upcast material from which the bank itself was built. Ringforts of this kind, known in Irish as raths, were the typical enclosed farmsteads of early medieval Ireland, built and occupied roughly between the fifth and twelfth centuries, and thousands of them survive in varying condition across the country. This one does not survive well.

The site sits on a south-east facing slope of a prominent hill in grassland, positioned to take in wide views of the surrounding hilly Westmeath countryside, which is typical of the pattern seen in ringfort placement across Ireland, where elevation and outlook were clearly factors in siting. The perimeter had already been partly quarried away along its northern to eastern arc before any formal record was made, and a field fence running north-east to south-west, shown on the 1837 edition of the Ordnance Survey six-inch map as a roadway, cuts through the monument at the north-west. That older road line, long since demoted to a field boundary, speaks to centuries of gradual encroachment and repurposing. By the time of the 2011 aerial photograph, the enclosing bank had been mainly levelled, leaving the interior's gentle south-westward slope and that single surviving bank remnant as the only legible traces of the original form.