The circular enclosure at Boystown in County Wicklow does none of that. At ground level, the site is simply invisible, a stretch of ordinary farmland on a gentle north-facing slope with nothing to catch the eye or slow the step. The enclosure exists, rather, as a ghost in the grain, a cropmark legible only from the air, where the buried ditch that once defined it causes the vegetation above to grow and colour differently from the surrounding soil.

What the aerial photographs reveal is a roughly circular form, approximately forty metres in diameter, defined by a fosse. A fosse is a ditch dug to mark or defend a boundary, and in Irish archaeology such circular ditched enclosures are associated with a broad range of functions and periods, from early medieval ringforts used as farmsteads to prehistoric ceremonial sites. The Boystown example sits quietly on its slope in Wicklow without, at present, enough evidence to say with confidence which tradition it belongs to. That ambiguity is part of what makes cropmark sites genuinely interesting: they preserve the shape of human activity while withholding almost everything else.