At Tomcoyle in County Wicklow, a circular enclosure some 32 metres in diameter occupies a gentle north-east-facing slope, known to archaeology but invisible to anyone standing on the ground above it. No earthwork survives to catch the light at dusk, no raised rim, no obvious hollow. The site is, in the most literal sense, a presence that can only be read rather than seen.

The enclosure was recorded by the Ordnance Survey during its pioneering six-inch mapping of Ireland in 1838, rendered on that sheet using hachures, the small radiating lines that cartographers of the period used to indicate a circular earthwork or ringfort boundary. Ringforts, which are typically enclosed farmsteads of the early medieval period, are among the most common archaeological monument types in Ireland, and Tomcoyle's enclosure falls within the size range typical of that tradition, though no further detail survives to confirm its date or function with certainty. By the time the site was formally catalogued in the late twentieth century, nothing remained at ground level. Whether it was ploughed out, eroded, or simply too slight to survive in recognisable form is not recorded.