A cashel, as this type of monument is known, is a ringfort defined by a dry-stone wall rather than an earthen bank or ditch, and this one at Lissylisheen is a quietly substantial example: roughly subcircular, about 31 metres east to west and 29 metres north to south, with a wall that still stands between 1.2 and 2 metres high and runs to between 2.2 and 2.3 metres wide. Its outer face is largely buried under accumulated stone and earth, giving it the look of a low grassy ridge rather than a wall at first glance. The site sits within a large multiperiod field system, meaning the surrounding landscape has been divided and worked across several distinct eras, making Lissylisheen part of a much older and more layered agricultural world.

The entrance, at the eastern side, is just a metre wide, and two stones projecting from the passage walls narrow it further to about 0.7 metres. T. J. Westropp, the Clare antiquarian who documented the site in 1899, described this as a narrow gateway with doorposts set at the inner corners. The site appears on the Ordnance Survey six-inch map as early as 1842, indicated by hachuring, the cartographic convention of the period for showing earthworks and enclosures. By 1897 it was labelled by name, and Robinson's map of 1977 gives the Irish form as Lios Uí Ghlaisín, a rendering that may follow James Frost's work from 1893. Inside the cashel, the remains of interior structures survive in various states of collapse: an L-shaped wall near the entrance, a collapsed wall to the north, and a U-shaped structure in the western interior that may once have been a house. A cairn of loose stones, about six metres in diameter, sits against the southern arc of the enclosing wall, its original purpose unrecorded. A wider gap in the northeast wall appears to be a modern breach rather than an original feature.