2 metres above the surrounding farmland near the Ballyboghill stream does not immediately announce itself as ancient, but the geometry is too deliberate to be accidental. This is almost certainly a platform ringfort, a variant of the more familiar type in which the enclosed area is raised above the surrounding ground rather than simply encircled by a bank and ditch. Platform ringforts are thought to date broadly to the early medieval period in Ireland, roughly the fifth to twelfth centuries, and were likely the homesteads of farming families of modest social standing, the raised ground offering both drainage and a degree of visual prominence.

The site at Leastown was already recorded simply as "fort" on the Ordnance Survey six-inch map of 1837, which suggests it was a recognised feature of the landscape well before archaeological survey caught up with it. The platform measures approximately 37 metres north to south and 38 metres east to west, with a possible ramped entrance on the southwestern side. There was once an outer fosse, essentially a surrounding ditch, which was still traceable in 1950, but it has since silted up entirely and is no longer visible at ground level. The surrounding field has undergone land clearance and re-fencing, and the perimeter of the platform itself has been planted with beech and sycamore, giving it the look of a deliberate enclosure. The site was discussed by Healy in 1975 and compiled as part of a broader survey by Geraldine Stout.

The ringfort sits on a natural rise that slopes away towards the Ballyboghill stream to the southwest, a topographical logic common to early medieval settlement sites, where slight elevation meant better drainage and a clearer view of the surrounding land. The ring of planted trees now marks the edge of the platform more clearly than any earthwork does, and walking around the base gives a reasonable sense of its scale. The silted-up fosse is no longer legible from the surface, so do not expect a visible ditch; the platform itself, and the way the ground falls away from it, is what repays attention.