The Annals of the Four Masters describe Turgéis, a Norwegian, as the 'lord of the foreigners' in the year 843, a title that conveys something of his reach and authority during a period of intense Scandinavian activity across the island. Whether he ever actually occupied this particular site is impossible to say with certainty, but the association is old enough to have been recorded on the Ordnance Survey Fair Plan map, where it appears as 'Rahindoon or Turgesius' Fort', and on the revised 1875 map simply as 'Turgesius' Fort'. The name has stuck.

The enclosure itself sits at the western end of a long natural ridge, roughly 800 metres south-southwest of Lough Lene. The southwestern face of the hill drops away almost like a cliff, and the outer edge of the inner bank runs close to that steep edge, making the most of the natural defensive topography. The monument is substantial: roughly 50 metres north to south and about 55 metres across on its wider axis. It is bounded by a massive earth and stone bank, with a narrow rock-cut fosse, or defensive ditch, cut into the bedrock at its outer foot, and the remains of a counterscarp bank beyond that. The entrance survives on the north-northwest side as a gap three metres wide in the inner bank, with a causeway, just over two metres wide and seven and a half metres long, carrying access across the fosse. Inside, the ground slopes from east to west and shows considerable disturbance. Two shallow depressions cross the interior at right angles to one another, likely the remnants of old drainage channels, and the four quadrants they define show faint traces of cultivation ridges, suggesting the enclosed area was put to agricultural use at some point after whatever earlier function it served. Natural rock outcrops are visible in the outer face of the bank on the eastern and southeastern sides, and quarrying activity has left traces just outside the monument to the southeast.