Sheela-na-gig figures are architectural sculpture, set as corbels, keystones or panels over doorways, windows and on castle and church walls, usually at a height where a visitor entering below would pass beneath the figure. Ireland holds the largest surviving count, over a hundred documented examples, with Britain a distant second and smaller numbers recorded in France and Spain; the concentration in Ireland is itself one of the facts scholarship has to explain, since the carvings are not evenly spread across the medieval Christian world that produced comparable grotesque and apotropaic sculpture generally.
Dating rests mainly on the fabric of the building a figure is set into rather than on the carving alone: most confidently dated examples belong to Romanesque and later medieval church and castle building between the twelfth and sixteenth centuries, such as the well known corbel series at Kilpeck in Herefordshire. A number of figures were removed, reburied or deliberately damaged from the eighteenth and nineteenth centuries onward as later generations found them indecent, and some were found built back into walls as reused masonry, occasionally upside down, evidence about later attitudes to the carvings even where their original purpose stays unsettled.