The earthwork in Crowinstown Great, County Westmeath, does not quite behave that way. Sitting on flat, well-drained grassland, it presents a raised sub-circular platform, roughly 25 metres north to south and 28 metres east to west, enclosed by two earthen banks with a wide intervening fosse, that is, a ditch, and a shallower outer fosse beyond that. There is an entrance gap in the inner bank at the south-east, and the interior rises slightly toward the centre. So far, so recognisable. What complicates things is a flat berm, a level shelf of ground, sitting between the inner platform and the outer bank, roughly six metres wide. That feature does not belong in the standard ringfort picture.

A classic bivallate ringfort, one with two concentric banks, tends to have its ditches and banks running in fairly close, consistent sequence. Here the geometry is different, giving the monument the profile of a concentric enclosure rather than a straightforward defended farmstead. The flat berm has prompted some debate. It may be the result of landscaping carried out after 1700, when estate improvement and field reorganisation could subtly or significantly alter earlier earthworks. Alternatively, it might indicate a different origin altogether. The slightly raised central platform has led to the suggestion that this could be the remains of a barrow, a burial mound, though that interpretation is offered cautiously and remains uncertain. What can be said is that the monument sits somewhere between categories, which in itself makes it worth attention.