What survives at Mylestown is a ringfort, known in Irish as a rath, the type of enclosed farmstead that was the basic unit of rural settlement across Ireland from roughly the sixth to the twelfth century. Thousands were built, and thousands have been erased, but this one occupies a curious middle ground: present enough to measure, absent enough to almost miss.

The monument was already being recorded as a roughly circular earthwork on the Ordnance Survey six-inch map of 1837, which places it firmly in the documentary record even as the physical structure was deteriorating. When surveyors described it in detail between 1970 and 1972, they found an oval enclosure measuring around 25.5 metres on its northwest to southeast axis and 22 metres across the northeast to southwest, enclosed by a bank and an external fosse. A fosse is simply a defensive ditch dug around the outer edge of the bank, and here the U-shaped channel survives visibly only along the western, northern, and eastern arcs. The bank itself, where it has not been reduced to a low scarp of around 1.1 metres, can still be made out from the west-southwest around to the north-northwest. No original entrance feature remains legible. Inside the enclosure, the ground slopes gently to the southwest, and broad cultivation ridges running northeast to southwest tell a later story: at some point after the ringfort fell out of use, the interior was pressed into agricultural service, the furrows of lazy-bed cultivation cutting across whatever domestic archaeology might lie beneath.

What the eye cannot fully read at ground level, aerial photography has partially restored. A levelled portion of the ringfort shows up as a circular cropmark on aerial imagery, the buried archaeology influencing the growth of grass above it in subtly different patterns depending on the season and the moisture in the soil. It is a quiet reminder that even where a monument appears to have been lost, it has a habit of reasserting itself from above.