That kind of quiet accommodation between different eras of land use is not unusual in the Irish countryside, but it is rarely so clearly legible in the ground itself.

A rath is a ringfort, the most common monument type in Ireland, typically dating from the early medieval period roughly between the fifth and twelfth centuries, and understood to represent the enclosed farmstead of a single family or small community. This one at Lismiraun sits on a ridge top in County Mayo, commanding very good views across the surrounding landscape, with a stream running along the base of the slope some 190 metres to the west. The roughly circular platform measures about 28 metres in diameter and is defined by a combination of scarp and earthen bank, with a fosse, that is a defensive ditch, and an outer bank enclosing it further. The inner bank survives best on the eastern side, where it remains a compact gravelly earthen construction up to 1.6 metres in external height, while to the north and west it has been worn down to little more than a low rise, partly obscured by overgrowth. The fosse, around 4.3 metres wide, is most visible on the southern and western arc, where it has been cut into rising ground in a way that naturally deepens its profile. The outer bank on the south-western side incorporates a considerable amount of stone, some of which may have been added later as field clearance material. An entrance gap about 2 metres wide survives on the north-east, with a large prostrate stone marking its southern terminal. The interior is now largely impenetrable, choked with dense blackthorn scrub. A second rath lies just 175 metres to the north, and an area of the ridge slope immediately north of this one shows signs of having been quarried at some point, the scar now similarly engulfed in blackthorn.