At Garreens in County Mayo, a roughly oval embanked enclosure once occupied a stretch of gently undulating grassland just south of a farmstead. It measured somewhere between 22 and 25 metres north to south and around 35 metres east to west, large enough to have been a substantial presence in the landscape. Today, there is no visible trace of it at ground level.

The enclosure appears clearly on the 1838 Ordnance Survey six-inch map, one of the most detailed cartographic records of the Irish countryside ever produced, and its outline is still legible on the 1930 edition, where an arc of hachuring, the fine lines surveyors used to indicate raised earthworks or banks, curves from the north-west toward the south-east. At some point between that mid-twentieth-century survey and the present day, the enclosure was levelled and absorbed into the garden and farmyard of the neighbouring farmstead. Embanked enclosures of this type are broadly associated with early medieval settlement in Ireland, sometimes surrounding a dwelling, a religious foundation, or an area of enclosed agricultural activity, though without excavation it is rarely possible to say more than that. What the people at Garreens were enclosing, and why, remains unknown.