Visible only in a 2005 aerial photograph as a crop mark, the faint outline of a roughly circular enclosure suggests the buried remains of a ringfort, the type of enclosed farmstead that served as the basic unit of rural settlement in early medieval Ireland. Thousands of ringforts survive across the country, but many more have been reduced over centuries of agriculture to precisely this: a ghostly trace, legible only from the air when differences in soil moisture cause crops growing above buried ditches and banks to ripen at a different rate from those around them.