This is a rath, the Irish term for a ringfort, the most common monument type in the Irish landscape. Ringforts were enclosed farmsteads of the early medieval period, roughly between the fifth and twelfth centuries, where a family and their livestock sheltered within a bank and ditch against the ordinary hazards of rural life. They were not military fortifications in any grand sense, but rather the farmyard boundaries of their age, and Boolanlisheen's example is a well-preserved specimen of the type.

The monument first appears cartographically on the Ordnance Survey Ireland six-inch map of 1840, recorded as a circular enclosure. By the time the twenty-five-inch edition was published in 1897, it had been annotated with the placename Boolanlisheen and its outline showed as an oval, measuring roughly 47 metres on a northeast to southwest axis and 35 metres across. When the Archaeological Survey of Ireland visited in 1999, they found a raised, roughly circular area approximately 42 metres north to south and 38 metres east to west, enclosed by a bank some eight metres wide and 1.4 metres high along its northern, southern, and western arcs. On the eastern side, the bank has been reduced to a scarp at the same height, incorporated into a field boundary. An external fosse, a shallow ditch outside the bank, survives along the northern, southern, and western stretches at a width of around 1.9 metres. The interior tilts noticeably downward toward the northwest, and the monument has been clipped at its northern and western edges by a field boundary running northeast to southwest.

The site sits about 70 metres south of a local road, within pasture that has been improved over the years, which accounts in part for the gradual erosion of the eastern side into a farm boundary. Those wanting to get a sense of the overall form before visiting will find, as the survey notes suggest, that the outline shows clearly on Google Earth satellite imagery, the bank casting enough shadow and relief to read as a distinct circle from above. On the ground, the surviving bank to the north, south, and west gives the clearest impression of the original enclosure, while the interior's slope toward the northwest is noticeable underfoot. Access would require permission from the landowner, as the fort lies within a working agricultural field.