It is a subrectangular enclosure, roughly 24 metres along its north-northwest to south-southeast axis and 18 metres across, defined by a low, irregular bank of earth and an outer fosse, which is simply a ditch dug along the outer edge of the bank. What makes it quietly puzzling is that nobody is quite sure what it was for.

The uncertainty here is genuine rather than routine. Most earthwork enclosures in Ireland can be provisionally assigned to a category, whether as a ringfort, a cashel, a field boundary, or a monastic precinct, but this one resists that kind of confident labelling. Its subrectangular shape and relatively modest scale set it apart from the typical circular farmstead enclosures of the early medieval period. One possibility recorded by McCaffrey in 1952 is that it may be a designed landscape feature rather than a functional or defensive structure, suggesting it could be a relatively deliberate piece of shaping in what was already difficult, waterlogged ground. The name Monksfield implies some historical connection to ecclesiastical land use in the area, which adds an intriguing layer without resolving anything.