The enclosure at An Tardán Thiar is subcircular in plan, measuring roughly 33 metres east to west, and what little survives of it is a grassed-over stone wall running from the south-west to the north-east. Beyond that arc, no surface trace remains.

Ringforts, known in Irish as ráth or lios depending on whether they were built from earthen banks or stone, were the most common form of enclosed farmstead in early medieval Ireland, in use roughly between the fifth and twelfth centuries. Thousands survive across the country in varying states of preservation, but the one at An Tardán Thiar sits at the lower end of that spectrum. Its position on a glacial ridge, a long narrow landform left behind by retreating ice sheets, would once have made it a commanding spot, with open views south across Lough Corrib. The ridge provided both elevation and, likely, well-drained ground, practical considerations that mattered as much as any defensive ones. That context makes the site legible even in its reduced state, though the south-eastern portion of the interior is now occupied by a modern bungalow, which complicates any reading of the original layout.