Somewhere beneath the ordinary pasture on this gently elevated ground in County Mayo, a ringfort has vanished so completely that by 1930 the Ordnance Survey no longer thought it worth marking. What had been a substantial embanked enclosure, roughly D-shaped and measuring some 30 metres north to south, had been levelled without leaving so much as a ripple in the grass.

The 1838 OS six-inch map recorded the site as a subcircular embanked enclosure, its eastern edge already clipped by a field fence running north to south. By the time the 25-inch plan was made, that fence had effectively reshaped the monument, giving it its flat eastern side and reducing what may once have been a full ring to a D. Ringforts, broadly speaking, are enclosed farmsteads of the early medieval period, their earthen banks offering both a degree of security and a clear statement of a family's presence on the land. The one at Treanlaur was never a large example, but it occupied a position with a clear view over the low-lying pasture below, the kind of modest but deliberate placement that is typical of the type. What finished it off entirely, and when, is not recorded.

What survives, if anything does, may lie underground. Local tradition holds that the site contains a souterrain, an artificially constructed underground passage or chamber associated with early medieval settlement, sometimes used for storage and sometimes as a refuge. The souterrain has its own separate record, suggesting the tradition has been taken seriously enough to note, even if nothing at the surface confirms it. The land gives no indication of what it may still be holding.