A turlough is a seasonal lake, a peculiarity of the Irish midlands and west, where water rises through limestone in winter and retreats again in summer, leaving behind a wet grassland that resists most forms of development. The enclosure at Lissananny sits on level pastureland near the northern edge of one such area, which is perhaps part of why so little of it survives.

When the first edition of the Ordnance Survey six-inch map was made in the nineteenth century, a circular enclosure roughly thirty metres in diameter was recorded here. Even then it had already been cut through by a field boundary running east to west across it, suggesting agricultural activity had long since begun to overwrite whatever the original structure had been. Circular enclosures of this kind are typically associated with early medieval settlement in Ireland, most commonly the type known as a ringfort, a raised circular area enclosed by an earthen bank and sometimes a ditch, used as a farmstead or place of habitation. Whether that is what this was remains uncertain. Today, only the most tentative trace of a bank survives along the southern limits of the site. The rest has gone, flattened by centuries of farming or perhaps absorbed back into the waterlogged ground that defines this particular corner of north Galway.